Phosphor and manufacturing method therefore, and light emission device using the phosphor

ABSTRACT

Provided is the phosphor expressed by a general composition formula MmAaBbOoNn:Z (where element M is one or more kinds of elements having bivalent valency, element A is one or more kinds of elements having tervalent valency, element B is one or more kinds of elements having tetravalent valency, O is oxygen, N is nitrogen, and element Z is one or more kinds of activators.), satisfying 4.0&lt;(a+b)/m&lt;7.0, a/m≧0.5, b/a&gt;2.5, n&gt;o, n=2/3m+a+4/3b−2/3o, and having an emission spectrum with a peak wavelength of 500 nm to 650 nm when excited by light in a wavelength range from 300 nm to 500 nm.

This is a Continuation of application Ser. No. 12/912,179 filed Oct. 26,2010, which is a Division of application Ser. No. 11/885,439 filed Aug.31, 2007, now U.S. Pat. No. 7,887,718, issued Feb. 15, 2011, which inturn is a National Phase of Application No. PCT/JP2006/304175 filed Mar.3, 2006, which claims priority to Japanese Patent Application Nos.2005-192691 filed Jun. 30, 2005, 2005-075854 filed Mar. 16, 2005, and2005-061627 filed Mar. 4, 2005. The disclosure of the prior applicationsis hereby incorporated by reference herein in their entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a phosphor containing nitrogen used fora display such as a cathode-ray tube (CRT), a field emission display(FED) and a plasma display (PDP), and an illumination device such as afluorescent lamp and a fluorescent display tube, and an illuminationdevice such as a liquid crystal back light, and to a method ofmanufacturing the phosphor, and also to a phosphor mixture, a phosphorsheet, and a light emission device such as a white LED illumination inwhich a semiconductor light emitting element (LED) and this phosphor arecombined.

BACKGROUND OF THE INVENTION

At present, a discharge type fluorescent lamp and an incandescent bulbused as the illumination device involve problems that a harmfulsubstance such as mercury is contained, and life span is short. However,in recent years, a high luminance LED emitting light of nearultraviolet/ultraviolet to blue color has been developed in sequence,and the white LED illumination for the practical application of the nextgeneration has been actively studied and developed, in which the whitelight is created by mixing the light of the near ultraviolet/ultravioletto blue color generated from the LED and the light generated from thephosphor having an excitation band in a wavelength region thereof. Whenthe white LED illumination is put to practical use, since efficiency ofconverting electric energy into light is improved, less heat isgenerated and it is constituted of the LED and a phosphor, the white LEDhas advantages of good life span without burn-out of a filament like aconventional incandescent bulb and the harmful substance such as mercuryis not contained, and miniaturization of the illumination device isrealized, thus realizing an ideal illumination device.

Two systems are proposed as the system of the LED illumination. One ofthem is a multi-chip type system which creates white color by usingthree primary color LEDs such as high luminance red LED, green LED, andblue LED, and the other one is one-chip type system which creates whitecolor by combining a high luminance LED emitting light of nearultraviolet/ultraviolet to blue color and a phosphor excited by thelight of the near ultraviolet/ultraviolet to blue color emitted fromthis LED. When these two systems are compared from the viewpoint ofillumination, particularly in the one-chip type system, the phosphorhaving an emission spectrum with a broad peak is used, therefore theemission spectrum can be made closer to the spectrum of solar light, andtherefore the white light having excellent color rendering propertiescan be obtained, compared to the multi-chip type system. Further, theone-chip type system has many advantages such as a simplified drivecircuit, enabling miniaturization, eliminating an optical waveguide formixing colors, with no necessity of considering a difference in drivevoltage and optical output of each LED, and reducing a cost. Therefore,the one-chip type system, in which an LED and a phosphor are combined,is focused as an illumination of the next generation.

The white LED illumination, in which a high luminance blue LED and aphosphor emitting yellow color by being excited by the blue lightgenerated from the LED are combined, is given as one of the examples ofthe one chip type white LED illumination. Specifically, for example, ahigh luminance blue LED and an yellow phosphor (Y,Gd)₃,(Al,Ga)₅O₁₂:Ce(YAG:Ce), Tb₃Al₅O₁₂:Ce, Ca₃Sc₂Si₃O₁₂:Ce, and CaSc₂O₄:Cecan be combined. In the white LED illumination, white color is obtainedby using a complementary relation between the blue emission of the LEDand the yellow emission of the phosphor, thereby allowing less phosphorto be used. Further, the yellow phosphor YAG:Ce used for the white LEDillumination has an excitation spectrum with a peak near the wavelengthof 460 nm, thereby allowing emission with high efficiency, and has anemission spectrum with a luminance (visibility) peak at about 560 nm,thereby allowing high luminance white LED to be obtained. However, theproblem of the white LED illumination is that the emission on thelonger-wavelength side of visible light range, specifically the emissionof red color component is insufficient, and therefore, only slightlybluish white emission can be obtained, and a slightly reddish whiteemission like an electric bulb can not be obtained, thereby the colorrendering properties are insufficient. However, in recent years, anitrogen-containing phosphor having a broad emission spectrum with apeak in a wavelength range from yellow color to red color, and alsohaving a good excitation band in a range from nearultraviolet/ultraviolet to blue color has been developed in sequence.Then, by adding such a phosphor, the color rendering properties areimproved.

Also, another example of the one chip type white LED illuminationobtains white color by using a mixed color of lights of the LED emittingthe near ultraviolet/ultraviolet color, and lights of the phosphoremitting red color (R), the phosphor emitting green color (G) and thephosphor emitting blue (B) color, obtained by being excited by the nearultraviolet/ultraviolet light generated from the LED. A method ofobtaining white emission by the lights of the R, G, B, and other colorsis capable of obtaining an arbitrary emission color other than whitelight, depending on the combination and mixed ratio of the R, G, B, andis excellent in color rendering properties, because the white emissionis obtained not by the complementary relation of the lights but by therelation of mixed colors using the R,G,B.

Then, as the phosphor used for such an application, examples are givensuch as Y₂O₂S:Eu, La₂O₂S:Eu, 3.5MgO.0.5MgF₂.GeO₂:Mn, (La, Mn,Sm)₂O₂S.Ga₂O₃:Eu for the red phosphor, ZnS:Cu,Al, CaGa₂S₄:Eu,SrGa₂S₄:Eu, BaGa₂S₄:Eu, SrAl₂O₄:Eu, BAM:Eu,Mn, (Ba,Sr,Ca,Mg)₂SiO₄:Eu forthe green phosphor, and BAM:Eu, Sr₅(PO₄)₃Cl:Eu, ZnS:Ag, (Sr, Ca, Ba,Mg)₁₀(PO₄)₆Cl₂:Eu for the blue phosphor. However, the red phosphors outof the phosphors of three colors have a sharp emission spectrum, whilethe phosphors of other colors have broad emission spectra, therebyinvolving the problem that the color rendering properties of the whitelight obtained is unsatisfactory, and emission characteristic at a hightemperature is deteriorated. However, such a problem has also beensolved, as described above, by developing in sequence phosphorscontaining nitrogen, excellent in temperature characteristic andexcitation band characteristic, and emitting from yellow color to redcolor.

The problem involved in the phosphor emitting yellow color to red coloris substantially solved, by developing the nitrogen-containing phosphorhaving the emission spectrum with a peak in the wavelength range fromyellow color to red color, having a broad emission spectrum, and furtherhaving a good excitation band in the wavelength range from the nearultraviolet/ultraviolet to blue color. As the phosphor containingnitrogen as described above, Ca₂Si₅N₈:Eu, Sr₂Si₅N₈:Eu, Ba₂Si₅N₈:Eu,Ca_(x)(Al,Si)₁₂(O,N)₁₆:Eu(0<x≦1.5), CaAl₂Si₄N₈:Eu, CaAlSiN₃:Eu and soforth are typically given as examples.

Here, as a necessary factor as a light source for a general illuminationsuch as a white LED as described above, firstly a factor of brightnessand secondary a factor of color rendering properties are given. As thefirst factor of brightness, the brightness (luminance) as the lightsource and emission efficiency are given, and in the LED, are largelyinfluenced by the emission efficiency of the used semiconductor element,the emission efficiency of the used phosphor, and the structure of thewhite LED itself. As the second factor, the color rendering property, avalue showing reproducibility of the color by the light source is givenas an example, and generally an evaluation method of this colorrendering property is shown in JISZ8726 (1990). Therefore, the colorrendering property will be explained by using the evaluation method ofJISZ8726.

According to JISZ8726, the color rendering property of the light sourceis numerically expressed by a general color rendering index (Ra). Thisis a value obtained by evaluating a difference of colors between areference sample for color rendering evaluation illuminated by a samplelight source, and the reference sample illuminated by a reference lightapproximated a natural light, and when there is no difference betweenthem and they are completely the same values, the color rendering index(Ra) is 100. Even if color temperatures of the light sources are thesame, there is a difference in the way color is observed depending onthe color rendering index, and when the color rendering index is low, acolor is dull and appears dark. When the light source has a uniformdensity of light over an entire region of visible light, this lightsource has an excellent color rendering property.

The color rendering property is improved by development of theaforementioned new phosphor emitting light from yellow color to redcolor, and the next problem is the phosphors with the emission peakwavelength from green color to yellow color.

First, the problem involved in the yellow phosphor YAG:Ce is explainedby using FIG. 25. FIG. 25 is a graph showing the emission intensity(relative intensity) taken on the ordinate axis and the wavelength of anexcitation light taken on the abscissa axis, and showing an excitationspectrum obtained by measuring an intensity of the light having thewavelength of 559.2 nm emitting light when the YAG:Ce is excited by anexcitation light having the wavelength of 300 to 570 nm.

In the white LED illumination obtained by combining the high luminanceblue LED and the YAG:Ce phosphor emitting yellow color by being excitedby blue color generated from the LED, the YAG:Ce phosphor has ahigh-efficiency excitation band for the light having the wavelength of460 nm generated from the blue LED, and further, has an emissionspectrum with a peak near to the wavelength of 560 nm in which theluminance (visibility) is highest, thereby allowing a high luminancewhite LED illumination to be obtained. However, as clarified from FIG.25, the YAG:Ce phosphor has an emission characteristic of emitting thelight having the wavelength of 560 nm or around with high efficiency,when excited by the light having the wavelength of 460 nm. However,since the excitation band is narrow, the emission wavelength of the blueLED changes due to variation in manufacturing the blue LED, then if theemission wavelength is deviated from the range of an optimal excitationband of the YAG:Ce phosphor when excited by the blue light of the blueLED, disruption of balance between the blue color and yellow coloremission intensity occurs. Such a situation involves the problem thatcolor tone of the white light obtained by combining the blue light andthe yellow light is changed.

Further, this YAG:Ce phosphor has an excellent emission spectrum in thewavelength range from about 500 to 550 nm of green color component ofvisible light. Therefore, preferably the YAG:Ce phosphor is used as agreen phosphor of the white LED illumination in which the nearultravilet/ultraviolet LED, the red (R) color emitting phosphor, thegreen (G) color emitting phosphor, and the blue color (B) emittingphosphor are combined. However, when light-emitted by the nearultraviolet/ultraviolet light, as shown in FIG. 25, this YAG:Ce phosphorhas a low-efficiency excitation band in the emission wavelength (380 to410 nm or around in FIG. 25) of the near ultraviolet/ultraviolet LED.Therefore, the problem involved therein is that a sufficient emissioncan not be obtained, and the high luminance white LED illumination cannot be obtained.

Next, the problem involved in the green phosphor used in combinationwith the ultraviolet LED will be explained. As the white LEDillumination using the near ultraviolet/ultraviolet emitting LED and themixed colors of light of the red (R) color emitting phosphor, the green(G) color emitting phosphor, and the blue (B) color emitting phosphorobtained by being excited by the light of the nearultraviolet/ultraviolet light generated from the LED, the green phosphorsuch as ZnS:Cu,Al, SrAl₂O₄:Eu, BAM:Eu,Mn, (Ba, Sr, Ca, Mg)₂SiO₄:Eu arepresently used. Among the phosphors, there is a problem that a sulfidephosphor is significantly deteriorated in emission intensity, when heatis applied thereto, and further has no water-resisting property. Inaddition, an oxide phosphor does not have a good efficient excitationband in a broad range of the wavelength in the vicinity of the nearultraviolet/ultraviolet. Therefore, the problem involved therein is thatwhen the variation in emission wavelength occurs due to by variation inmanufacturing the near ultraviolet/ultraviolet LED, the emissionwavelength of the near ultraviolet/ultraviolet LED is deviated from theoptimal excitation range, thereby disrupting the balance in emissionintensity among the red color, green color, and blue color, resulting inthe change of the color tone of the white light.

Therefore, as the green to yellow emitting phosphor by being excited bythe light of the near ultraviolet/ultraviolet to blue color also, demandon a new phosphor having a flat high-efficiency excitation band in thewavelength range from near ultraviolet/ultraviolet to blue color, andhaving a broad emission spectrum, and further having an excellentdurability against heat and water, and replacing YAG:Ce phosphor andZnS:Cu,Al phosphor is increased. In order to respond to such a demand,green to yellow emitting phosphors are actively pursued, and in recentyears, silicon nitride-based phosphor (for example see patent document1), a phosphor comprising sialon as a matrix (for example, see patentdocuments 2, 3, 4), and oxynitride phosphor (for example, see patentdocuments 5 and 6) are proposed as the green to yellow emittingphosphor.

-   (Patent document 1) Japanese Patent Laid Open No. 2002-322474-   (Patent document 2) Japanese Patent Laid Open No. 2003-203504-   (Patent document 3) Japanese Patent Laid Open No. 2003-206481-   (Patent document 4) Japanese Patent Laid Open No. 2002-363554-   (Patent document 5) WO Publication No. 2004/029177 A1 pamphlet-   (Patent document 6) WO Publication No. 2004/055910 A1 pamphlet

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

However, although such a phosphor containing nitrogen has an excellentdurability against heat and water, has a flat excitation band in thewavelength range from near ultraviolet/ultraviolet to blue color, andhas an emission spectrum with a broad peak, the emission efficiency doesnot meet a satisfactory level when excited by the excitation light ofthe near ultraviolet/ultraviolet to blue color, and a sufficientemission intensity and luminance are not obtained. Therefore, althoughthe white LED illumination having an excellent durability can bemanufactured, the emission intensity and luminance are insufficient.Therefore, when the white LED illumination is manufactured by combiningthe near ultraviolet/ultraviolet LED, the blue LED or the like and theaforementioned phosphor containing nitrogen, the luminance which is amost important factor as the illumination becomes insufficient. Inaddition, as a demand of a market hereafter, the emission device capableof performing various emissions such as a white color emission havingexcellent emission efficiency, excellent luminance, and excellent colorrendering properties, are considered to be desired.

In view of the aforementioned problems, the present invention isprovided, and an object of the present invention is to provide aphosphor having a broad emission spectrum with a peak from green colorto yellow color, having a flat and wide excitation band in the rangefrom near ultraviolet/ultraviolet to blue color, and having an excellentemission efficiency and luminance, a manufacturing method thereof, aphosphor mixture using this phosphor, a phosphor sheet, and an emissiondevice such as a white LED illumination using such a phosphor, which hasan excellent emission efficiency, luminance and color renderingproperties.

Means to Solve the Problem

In order to solve the aforementioned problems, study on the response tothe emission device or a light source having an excellent luminance andexcellent color rendering properties is pursued. Then, as a result, itis found that the aforementioned problem can be solved by combining anyellow or green phosphor with a broad emission spectrum with a maximumpeak (the maximum peak of the emission spectrum is sometimes describedas simply a maximum peak hereunder) in a range from 520 nm to 580 nm,and having an excitation band in the light of a broad wavelength fromultraviolet to visible light (such as blue light), and phosphor of othercolors.

Namely, it is found that by creating a phosphor mixture by combiningthis green phosphor, red phosphor similarly having an excitation band inthe light with a broad wavelength from ultraviolet to visible light(such as blue light), and having the emission spectrum with a maximumpeak in the wavelength range from 590 nm to 680 nm, and/or blue phosphorhaving emission spectrum with a maximum peak in the range from 420 nm to500 nm, and when this phosphor mixture and various light sources (suchas light source from ultraviolet light to blue light) are combined, theemission device capable of causing various light emissions such as whiteemission having an excellent emission efficiency, with high luminance,and having excellent color rendering properties can be manufactured.

Therefore, study on already known green and yellow phosphors havingemission spectrum with a maximum peak in the range from 520 nm to 580 nmand the phosphor described in the patent document 3 are firstly studiedon. However, it is found that the already known green and yellowphosphors have low emission efficiency when the blue LED and theultraviolet LED are used as the excitation light, thus making itimpossible to obtain light emission with high luminance.

Therefore, in order to solve the aforementioned problems, study onvarious phosphor compositions containing nitrogen is pursued. Then, as aresult, it is found that a new phosphor having a broad and flatexcitation band in the range from near ultraviolet/ultraviolet to bluecolor, having an improved emission intensity and luminance in the rangefrom green color to yellow color, and having a broad emission spectrumcan be obtained by adjusting the phosphor with a matrix compositionhaving a site where Ce and Eu atoms can be easily and stably replaced.Further, it is found that the phosphor having excellent emissionintensity and luminance in the range from yellow color to red color isobtained, when Eu or the like is used as an activator.

Further, the above-described problem can be solved by developing aphosphor mixture obtained by mixing the green phosphor, one or morekinds of blue phosphor having an emission spectrum with a maximum peakin the wavelength range from 420 nm to 500 nm and/or one or more kindsof red phosphors having an emission spectrum with a maximum peak in thewavelength range form 590 nm to 680 nm, and further by developing anemission device having this phosphor mixture and an emission part foremitting light with the wavelength range from 300 nm to 500 nm.

In a first aspect in order to solve the above-mentioned problems, aphosphor is provided, which is given as a general composition formulaexpressed by MmAaBbOoNn:Z, (where element M is one or more kinds ofelements having bivalent valency, element A is one or more kinds ofelements having tervalent valency, element B is one or more kinds ofelements having tetravalent valency, O is oxygen, N is nitrogen, andelement Z is one or more kinds of activators.), satisfying4.0<(a+b)/m<7.0, a/m≧0.5, b/a>2.5, n>o, n=2/3m+a+4/3b−2/3o, wherein whenbeing excited by the light with the wavelength range from 300 nm to 500nm, the phosphor has an emission spectrum with a peak wavelength in arange from 500 nm to 650 nm.

In a second aspect, the phosphor according to the first aspect isprovided, satisfying 0.5≦a/m≦2.0, 3.0<b/m<7.0, 0<o/m≦4.0.

In a third aspect, the phosphor according to either of the first aspector the second aspect is provided, satisfying by 0.8≦a/m≦1.5,3.0<b/m<6.0, 0<o/m≦3.0.

In a fourth aspect, the phosphor according to any one of the first tothird aspects is provided, satisfying 1.1<a/m≦1.5, 3.5≦b/m≦4.5,0<o/m≦1.5.

In a fifth aspect, the phosphor according to any one of the first tofourth aspects is provided, wherein the element M is one or more kindsof elements selected from the group consisting of Mg, Ca, Sr, Ba, Zn,and rare earth elements having bivalent valnecy, the element A is one ormore kinds of elements selected from the group consisting of Al, Ga, In,Tl, Y, Sc, P, As, Sb, and Bi, the element B is one or more kinds ofelements selected from the group consisting of Si, Ge, Sn, Ti, Hf, Mo,W, Cr, Pb, and Zr, and the element Z is one or more kinds of elementsselected from rare earth elements and transition metal elements.

In a sixth aspect, the phosphor according to any one of the first tofifth aspects is provided, wherein the element M is one or more kinds ofelements selected from the group consisting of Mg, Ca, Sr, Ba, and Zn,the element A is one or more kinds of elements selected from the groupconsisting of Al, Ga, and In, the element B is Si and/or Ge, and theelement Z is one or more kinds of elements selected from the groupconsisting of Eu, Ce, Pr, Tb, and Mn.

In a seventh aspect, the phosphor according to any one of the first tosixth aspects is provided, wherein the element M is Sr, the element A isAl, the element B is Si, and the element Z is Eu and/or Ce.

In an eighth aspect, the phosphor according to any one of the first toseventh aspects is provided, wherein when the general formula isexpressed by MmAaBbOoNn:Zz, the value of z/(m+z), which is a molar ratioof the element M to the element Z, is not less than 0.0001 and not morethan 0.5.

In a ninth aspect, the phosphor according to any one of the first toeighth aspects is provided, containing Sr of 19.5 to 29.5 wt %, Al of5.0 to 16.8 wt %, O of 0.5 to 8.1 wt %, N of 26.0 to 32.0 wt %, and Ceof more than 0 to 3.5 wt % or less, wherein when the phosphor isirradiated with one or more kinds of monochromatic lights or continuouslights having the wavelength range from 350 nm to 500 nm as anexcitation light, a peak wavelength in the emission spectrum is in therange from 500 to 600 nm, and x of chromaticity (x, y) of the emissionspectrum is in the range from 0.3000 to 0.4500, and y of thechromaticity (x, y) is in the range from 0.5000 to 0.6000.

In a tenth aspect, the phosphor according to any one of the first toeighth aspects is provided, containing Sr of 19.5 to 29.5 wt %, Al of5.0 to 16.8 wt %, O of 0.5 to 8.1 wt %, N of 22.6 to 32.0 wt %, and Euof more than 0 to 3.5 wt % or less, wherein when the phosphor isirradiated with one or more kinds of monochromatic lights or continuouslights having the wavelength range from 350 nm to 500 nm as anexcitation light, the peak wavelength of the emission spectrum is in therange from 550 to 650 nm, and x of the chromaticity of the emissionspectrum (x, y) is in the range from 0.4500 to 0.6000, and y of thechromaticity of the emission spectrum (x, y) is in the range from 0.3500to 0.5000.

In an eleventh aspect, the phosphor according to the tenth aspect isprovided, wherein when the phosphor is irradiated with the monochromaticlight having the wavelength range from 350 nm to 500 nm as an excitationlight, the relation of P_(H) and P_(L) is given satisfying(P_(H)−P_(L))/P_(H)×100≦20, when a peak intensity of a maximum peak in aspectrum of light emission that occurs by absorbing the excitation lightthat makes it highest is defined as P_(H), and the peak intensity of themaximum peak in the spectrum of light emission that occurs by absorbingthe excitation light that makes it smallest is defined as P_(L).

In a twelfth aspect, the phosphor according to any one of the first toeleventh aspects is provided, wherein when the value of relativeintensity of the maximum peak in the emission spectrum is defined as P₂₅when the phosphor is irradiated with a specified monochromatic light inthe wavelength range from 300 nm to 500 nm as the excitation light at25° C., and the value of the relative intensity of the maximum peak isdefined as P₂₀₀ when the phosphor is irradiated with the specifiedmonochromatic light as the excitation light at 200° C., the relation ofP₂₅ and P₂₀₀ is given satisfying (P₂₅−P₂₀₀)/P₂₅×100≦35.

In a thirteenth aspect, the phosphor according to any one of the firstto twelfth aspects is provided, containing primary particles withparticle size of 50 μm or less and aggregates in which the primaryparticles agglutinate, wherein an average particle size (D50) of thepowdery phosphor containing the primary particles and the aggregates is1.0 μm or more and 50.0 μm or less.

In a fourteenth aspect, the phosphor according to any one of the firstto thirteenth aspects is provided, containing the primary particles withparticle size of 20 μm or less and the aggregates in which the primaryparticles agglutinate, wherein the average particle size (D50) of thepowdery phosphor containing the primary particles and the aggregates is1.0 μm or more and 20.0 μm or less.

In a fifteenth aspect, a method of manufacturing the phosphor accordingto any one of the first to fourteenth aspects is provided, wherein byusing a crucible composed of nitride as a firing crucible, raw materialsare fired at temperature of 1400° C. or more and 2000° C. or less in anatmosphere containing one or more kinds of gases selected from nitrogengas, rare gas, and ammonia gas.

In a sixteenth aspect, the method of manufacturing the phosphoraccording to the fifteenth aspect is provided, wherein the raw materialsare fired by setting pressure inside furnace at 0.001 MPa or more and0.5 MPa or less.

In a seventeenth aspect, the method of manufacturing the phosphoraccording to either of the fifteenth or sixteenth aspect is provided,wherein the crucible composed of nitride is a BN crucible.

In an eighteenth aspect, the method of manufacturing the phosphoraccording to any one of the fifteenth to seventeenth aspects isprovided, wherein the raw materials are fired, with 0.1 ml/min or moregas containing one or more kinds of gases selected from the nitrogengas, rare gas, and the ammonia gas flowing inside the furnace.

In a nineteenth aspect, the method of manufacturing the phosphoraccording to the eighteenth aspect is provided, wherein a gas containing80% or more of nitrogen gas is used as an atmosphere gas inside saidfurnace.

In a twentieth aspect, the method of manufacturing the phosphoraccording to any one of the fifteenth to nineteenth aspect is provided,wherein by using raw material particles of 10 μm or less, the rawmaterial is fired in a powdery state.

In a twenty-first aspect, a phosphor mixture is provided, including thephosphor described in any one of the first to fourteenth aspects, one ormore kinds of blue phosphors having the emission spectrum with a maximumpeak in the wavelength range from 420 nm to 500 nm, when being excitedwith said excitation light in the wavelength range from 300 nm to 500nm, and/or one or more kinds of red phosphors having the emissionspectrum with a maximum peak in the wavelength range from 590 nm to 680nm, when being excited with the excitation light in the wavelength rangefrom 300 nm to 500 nm.

In a twenty-second aspect, a phosphor mixture is provided, including thephosphor described in any one of the first to fourteenth aspects, one ormore kinds of blue phosphors having the emission spectrum with a maximumpeak in the wavelength range form 420 nm to 500 nm when being excited bysaid excitation light in the wavelength range from 300 nm to 420 nm, andone or more kinds of red phosphors having the emission spectrum with amaximum peak in the wavelength range from 590 nm to 680 nm, when beingexcited with the excitation light in the wavelength range from 300 nm to420 nm.

In a twenty-third aspect, a phosphor mixture is provided, which is thephosphor mixture according to the twenty-first or twenty-second aspect,wherein when emission intensity of each phosphor constituting themixture at a temperature of 25° C. when being excited by a specifiedexcitation light in the wavelength range from 300 nm to 500 nm isdefined as P₂₅, and the emission intensity at a temperature of 200° C.when being excited by said specified excitation light is defined asP₂₀₀, 200, ((P₂₅−P₂₀₀)/P₂₅)×100≦30.

In a twenty-fourth aspect, the phosphor mixture according to thetwenty-first or twenty-third aspect is provided, wherein in the emissionspectrum under excitation of the excitation light in a range from 300 nmto 420 nm, a correlated color temperature is in a range from 7000K to2500K, with three or more emission peaks in the wavelength range from420 nm to 750 nm and with a continuous spectrum without beinginterrupted in the wavelength range from 420 nm to 780 nm.

In a twenty-fifth aspect, the phosphor mixture according to any one ofthe twenty-first to twenty-fourth aspects is provided, wherein a redphosphor having the emission spectrum with a peak in the wavelengthrange from 590 nm to 680 nm is given as a general composition formulaexpressed by MmAaBbOoNn:Z, (where the element M is one or more kinds ofelements selected from the group consisting of Ca, Mg, Sr, Ba, and Zn,the element A is one or more kinds of elements selected from the groupconsisting of Al, Ga, and In, the element B is one or more kinds ofelements selected from the group consisting of Si, Ge, and Sn, and theelement Z is one or more kinds of elements selected from rare earthelements and transition metal elements), satisfying n=2/3m+a+4/3b−2/3o,m=1, a≧0, b≧m, n>o, o≦0).

In a twenty-sixth aspect, the phosphor mixture according to thetwenty-fifth aspect is provided, wherein the red phosphor having theemission spectrum with the maximum peak in the wavelength range from 590nm to 680 nm meets the equation of m=a=b=1, and n=3, having thecomposition formula expressed by CaAlSiN₃:Eu.

In a twenty-seventh aspect, the phosphor mixture according to any of thetwenty-first to twenty-sixth aspect is provided, wherein a blue phosphorhaving the emission spectrum with a maximum peak in the wavelength rangefrom 420 nm to 500 nm is one or more kinds of phosphors selected fromBAM:Eu(BaMgAl₁₀O₁₇:Eu), (Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu.

In a twenty-eighth aspect, the phosphor mixture according to any one ofthe twenty-first to twenty-seventh aspects is provided, wherein thephosphor mixture is composed of a phosphor having an average particlesize (D50) of 1 μm or more and 50 μm or less.

In a twenty-ninth aspect, a phosphor sheet is provided, wherein thephosphor according to any one of the first to fourteenth aspects, or thephosphor mixture according to any one of the twenty-first totwenty-eighth aspects are dispersed in resin or glass.

In a thirtieth aspect, a light emission device is provided, having thephosphor according to anyone of the first to fourteenth aspects and alight emission part for emitting light of a first wavelength, whereinthe light of a different wavelength from the first wavelength is emittedfrom the phosphor, by using a part or an entire part of the light of thefirst wavelength as an excitation light.

In a thirty-first aspect, the light emission device is provided, havingthe phosphor mixture according to any one of the twenty-first totwenty-eighth aspects and the light emission part for emitting light ofthe first wavelength, wherein the light of the different wavelength fromthe first wavelength is emitted from the phosphor, by using a part or anentire part of the light of the first wavelength as an excitation light.

In a thirty-second aspect, a light emission device is provided, havingthe phosphor sheet of the twenty-ninth aspect and the light emissionpart for emitting light of the first wavelength, wherein the light ofthe different wavelength from the first wavelength is emitted from thephosphor, by using a part or an entire part of the light of the firstwavelength as an excitation light.

In a thirty-third aspect, a light emission device according to any oneof the thirtieth to thirty-second aspects is provided, wherein the firstwavelength is the wavelength of 350 nm to 500 nm.

In a thirty-fourth aspect, the light emission device according to anyone of the thirtieth to thirty-third aspects is provided, wherein thecorrelated color temperature of the light emission device is in a rangefrom 10000K to 2000K.

In a thirty-fifth aspect, the light emission device according to any oneof the thirtieth to thirty-fourth aspects is provided, wherein thecorrelated color temperature of the light emission device is in a rangefrom 7000K to 2500K.

In a thirty-sixth aspect, the light emission device according to any oneof the thirtieth to thirty-fifth aspects is provided, wherein an generalcolor rendering index Ra of the light emission device is 80 or more.

In a thirty-seventh aspect, the light emission device according to anyone of the thirtieth to thirty-sixth aspects is provided, wherein aspecial color rendering index R15 of the light emission device is 80 ormore.

In a thirty-eighth aspect, the light emission device according to anyone of the thirtieth to thirty-seventh aspects is provided, wherein aspecial color rendering index R9 of the light emission device is 60 ormore.

In a thirty-ninth aspect, the light emission device according to any oneof the thirtieth to thirty-eighth aspects is provided, wherein the lightemission part is a light emitting diode (LED).

In a fortieth aspect, a phosphor given as a general composition formulaexpressed by MmAaBbOoNn:Z, (where element M is one or more kinds ofelements having bivalent valency, element A is one or more kinds ofelements having tervalent valency, element B is one or more kinds ofelements having tetravalent valency, O is oxygen, N is nitrogen, andelement Z is one or more kinds of activators.), satisfying4.0<(a+b)/m<7.0, a/m≧0.5, b/a>2.5, n>o, n=2/3m+a+4/3b−2/3o.

In a forty-first aspect, the phosphor according to the fortieth aspectis provided, satisfying 0.5≦a/m≦1.5, 3.5<b/m<6.5, 0<o/m<4.0.

In a forty-second aspect, the phosphor according to the fortieth orforty-first aspect is provided, satisfying 0.8≦a/m≦1.2, 4.0≦b/m≦6.0,0<o/m≦3.0.

In a forty-third aspect, the phosphor according to any one of thefortieth to forty-second aspects is provided, wherein the element M isone or more kinds of elements selected from the group consisting of Mg,Ca, Sr, Ba, Zn and rare earth elements having bivalent valency, theelement A is one or more kinds of elements selected from the groupconsisting of Al, Ga, In, Tl, Y, Sc, P, As, Sb, and Bi, the element B isone or more kinds of elements selected from the group consisting of Si,Ge, Sn, Ti, Hf, Mo, W, Cr, Pb, Zr, and the element Z is one or morekinds of elements selected from the group consisting of rare earthelements and transition metal elements.

In a forty-forth aspect, the phosphor according to any one of thefortieth to forty-third aspects is provided, wherein the element M isone or more kinds of elements selected from the group consisting of Mg,Ca, Sr, Ba, Zn, the element A is one or more kinds of elements selectedfrom the group consisting of Al, Ga, In, the element B is Si and/or Ge,and the element Z is one or more kinds of elements selected from thegroup consisting of Eu, Ce, Pr, Tb, and Mn.

In a forty-fifth aspect, the phosphor according to any one of thefortieth to forty-forth aspects is provided, wherein the element M isSr, the element A is Al, the element B is Si, and the element Z is Euand/or Ce.

In a forty-sixth aspect, the phosphor according to any one of thefortieth to forty-fifth aspects is provided, wherein when the generalformula is expressed by MmAaBbOoNn:Zz, the value of z/(m+z), which is amolar ratio of the element M to the element Z, is 0.0001 or more and 0.5or less.

In a forty-seventh aspect, the phosphor according to any one of thefortieth to forty-sixth aspects is provided, which is given as formulasexpressed by: Sr₆Al₆Si₁₈O₃N₃₂:Ce, SrAlSi₃ON₅:Ce, Sr₃Al₃Si₉O₆N₁₃:Ce,Sr₆Al₆Si₂₄O₃N₄₀:Ce, Sr₃Al₃Si₁₂O₃N₁₉:Ce, Sr₃Al₃Si₁₂O₆N₁₇:Ce,Sr₆Al₆Si₂₇O₃N₄₄:Ce, Sr₂Al₂Si₉O₂N₁₄:Ce, Sr₆Al₆Si₂₇O₁₂N₃₈:Ce,Sr₂Al₂Si₁₀ON₁₆:Ce, Sr₃Al₃Si₁₅O₃N₂₃:Ce, SrAlSi₅O₂N₇:Ce,Sr₆Al₆Si₃₆O₃N₅₆:Ce, SrAlSi₆ON₉:Ce, Sr₃Al₃Si₁₈O₆N₂₅:Ce,Sr₆Al₆Si₁₈O₃N₃₂:Eu, SrAlSi₃ON₅:Eu, Sr₃Al₃Si₉O₆N₁₃:Eu,Sr₆Al₆Si₂₄O₃N₄₀:Eu, Sr₃A₁₃Si₁₂O₃N₁₉:Eu, Sr₃Al₃Si₁₂O₆N₁₇:Eu,Sr₆Al₆Si₂₇O₃N₄₄:Eu, Sr₂Al₂Si₉O₂N₁₄:Eu, Sr₆Al₆Si₂₇O₁₂N₃₈:Eu,Sr₂Al₂Si₁₀₀N₁₆:Eu, Sr₃Al₃Si₁₅O₃N₂₃:Eu, SrAlSi₅O₂N₇:Eu,Sr₆Al₆Si₃₆O₃N₅₆:Eu, SrAlSi₆ON₉:Eu, Sr₃Al₃Si₁₈O₆N₂₅:Eu.

In a forty-eighth aspect, the phosphor according to any one of fortiethto forty-seventh aspects, containing Sr of 20.0 to 27.0 wt %, Al of 5.0to 9.0 wt %, Si of 30.0 to 39.0 wt %, O of 0.5 to 6.0 wt %, N of 26.0 to32.0 wt %, and Ce of more than 0 to 3.5 wt % or less, wherein when thephosphor is irradiated with one or more kinds of monochromatic lights orcontinuous lights having the wavelength range from 350 nm to 500 nm asan excitation light, a peak wavelength in the emission spectrum is inthe range from 500 to 600 nm, and x of chromaticity (x, y) of theemission spectrum is in the range from 0.3500 to 0.4500, and y of thechromaticity (x, y) is in the range from 0.5000 to 0.6000.

In a forty-ninth aspect, the phosphor according to any one of thefortieth to forty-seventh aspects is provided, containing Sr of 20.0 to27.0 wt %, Al of 5.0 to 9.0 wt %, Si of 30.0 to 39.0 wt %, O of 0.5 to6.0 wt %, N of 26.0 to 32.0 wt %, and Eu of more than 0 to 3.5 wt % orless, wherein when the phosphor is irradiated with one or more kinds ofmonochromatic lights or continuous lights having the wavelength rangefrom 350 nm to 550 nm as an excitation light, the peak wavelength of theemission spectrum is in the range from 550 to 650 nm, and x of thechromaticity of the emission spectrum (x, y) is in the range from 0.4500to 0.6000, and y of the chromaticity of the emission spectrum (x, y) isin the range from 0.3500 to 0.5000.

In a fiftieth aspect, the phosphor according to the forty-ninth aspectis provided, wherein when the phosphor is irradiated with themonochromatic light having the wavelength range from 350 nm to 550 nm asan excitation light, the relation of P_(H) and P_(L) is given satisfying(P_(H)−P_(L))/P_(H)≦0.20, when a peak intensity of a maximum peak in aspectrum of light emission that occurs by absorbing the excitation lightthat makes the peak intensity highest is defined as P_(H), and the peakintensity of the maximum peak in the spectrum of light emission thatoccurs by absorbing the excitation light that makes the peak intensitysmallest is defined as P_(L).

In a fifty-first aspect, the phosphor according to any one of thefortieth to fiftieth aspects is provided, wherein in an X-ray powderdiffraction pattern by CoKα ray, when the maximum peak is defined as a,b, and c, respectively, with Bragg angle (20) in a range from 28.5° to29.5°, 35.5° to 36.5°, and 41.0° to 42.0°, and a peak intensity ratio ofa to b is defined as I(a/b), and the peak intensity ratio of c to b isdefined as I(c/b), the relation of a, b, c is given satisfying0.20<I(a/b), I(c/b)<1.50.

In a fifty-second aspect, the phosphor according to any one of thefortieth to fifty-first aspects is provided, wherein when the value ofrelative intensity of the maximum peak in the emission spectrum isdefined as P₂₅ when the phosphor is irradiated with a specifiedmonochromatic light in the wavelength range from 350 nm to 550 nm as theexcitation light at 25° C., and the value of the relative intensity ofthe maximum peak is defined as P₂₀₀ when the phosphor is irradiated withthe specified monochromatic light as the excitation light at 200° C.,the relation of P₂₅ and P₂₀₀ is given satisfying (P₂₅−P₂₀₀)/P₂₅×100≦35.

In a fifty-third aspect, the phosphor according to any one of thefortieth to fifty-second aspects is provided, wherein the phosphor is apowdery form.

In a fifty-forth aspect, the phosphor according to the fifty-thirdaspect is provided, containing primary particles with particle size of20 μm or less and aggregates in which the primary particles agglutinate,wherein an average particle size (D50) of the powdery phosphorcontaining the primary particles and the aggregates is 1.0 μm or moreand 20.0 μm or less.

In a fifty-fifth aspect, a phosphor mixture is provided, a greenphosphor given as a general composition formula expressed byMmAaBbOoNn:Z, (where element M is one or more kinds of elements havingbivalent valency, element A is one or more kinds of elements havingtervalent valency, element B is one or more kinds of elements havingtetravalent valency, O is oxygen, N is nitrogen, and element Z is anelement acting as an activator.), satisfying 4.0<(a+b)/m<7.0,0.5≦a/m≦2.0 m 3.0≦b/m≦7.0, 0<o/m≦5.0, n=2/3m+a+4/3b−2/3o, and includedtherein are:

a green phosphor having an emission spectrum with a maximum peak in awavelength range from 520 nm to 580 nm when the phosphor is irradiatedwith one or more kinds of monochromatic lights or continuous lights inthe wavelength range from 300 nm to 420 nm as an excitation light;

one or more kinds of blue phosphors having an emission spectrum with amaximum peak in a wavelength range from 420 nm to 500 nm when thephosphor is irradiated with the excitation light in a wavelength rangefrom 300 nm to 420 nm; and

one or more kinds of red phosphors having an emission spectrum with amaximum peak in a wavelength range from 590 nm to 680 nm when beingexcited with the excitation light in the wavelength range from 300 nm to420 nm.

In a fifty-sixth aspect, the phosphor mixture according to thefifty-fifth aspect is provided, wherein the green phosphor having theemission spectrum with a maximum peak in the wavelength range from 520nm to 580 nm satisfies 0.5≦a/m≦2.0, 4.0≦b/m≦6.0, 0<o/m≦3.0.

In a fifty-seventh aspect, the phosphor mixture according to thefifty-fifth aspect or the fifty-sixth aspect is provided, wherein

the element M is one or more kinds of elements selected from the groupconsisting of Ca, Mg, Sr, Ba, and Zn;

the element A is one or more kinds of elements selected from the groupconsisting of Al, Ga, and In;

the element B is one or more kinds of elements selected from the groupconsisting of Si, Ge, and Sn; and

the element Z is one or more kinds of elements selected from rare earthelements and transition metal elements.

In a fifty-eighth aspect, the phosphor mixture according to any one ofthe fifty-fifth to fifty-seventh aspects is provided, wherein theelement Z is Ce.

In a fifty-ninth aspect, the phosphor mixture is provided, wherein whenemission intensity of each phosphor constituting a mixture at atemperature of 25° C. when being excited by a specified excitation lightin the wavelength range from 300 nm to 420 nm is defined as P₂₅, and theemission intensity at a temperature of 200° C. when being excited bysaid specified excitation light is defined as P₂₀₀,((P₂₅−P₂₀₀)/P₂₅)×100≦30.

In a sixtieth aspect, the phosphor mixture according to any one of thefifty-fifth to fifty-ninth aspects is provided, wherein in the emissionspectrum under excitation of the excitation light in a range from 300 nmto 420 nm, a correlated color temperature is in a range from 7000K to2000K, with three or more emission peaks in the wavelength range from420 nm to 780 nm and with a continuous spectrum without beinginterrupted in the wavelength range from 420 nm to 780 nm.

In a sixty-first aspect, the phosphor mixture according to any one ofthe fifty-fifth to sixtieth aspects is provided, wherein the redphosphor having an emission spectrum with a maximum peak in thewavelength range from 590 nm to 680 nm is expressed by a compositionformula of MmAaBbOoNn:Z (where the element M is one or more kinds ofelements selected from the group consisting of Ca, Mg, Sr, Ba, and Zn,the element A is one or more kinds of elements selected from the groupconsisting of Al, Ga, and In, the element B is one or more kinds ofelements selected from the group consisting of Si, Ge, and Sn, and theelement Z is one or more kinds of elements selected from rare earthelements and transition metal elements, satisfying n=2/3m+a+4/3b−2/o,m=1, a≧0, b≧m, n>0, o>0).

In a sixty-second aspect, the phosphor mixture according to any one ofthe fifty-fifth to sixty-first aspects is provided, wherein the redphosphor having an emission spectrum with a maximum peak in thewavelength range from 590 nm to 680 nm meets the equation of m=a=b=1,and n=3, having a composition formula of CaAlSiN₃:Eu.

In a sixty-third aspect, the phosphor mixture according to any one ofthe fifty-fifth to sixty-second aspects is provided, wherein the bluephosphor having an emission spectrum with a maximum peak in thewavelength range from 420 nm to 500 nm is one or more kinds of phosphorselected from BAM:Eu (BaMgAl₁₀O₁₇:Eu), (Sr,Ca,Ba,Mg)₁₀ (PO₄)₆Cl₂:Eu.

In a sixty-forth aspect, the phosphor mixture according to any one ofthe fifty-fifth to sixty-third aspects is provided, wherein an averageparticle size (D50) of each phosphor containing the primary particle andthe aggregates is 1.0 μm or more and 20.0 μm or less.

In a sixty-fifth aspect, a phosphor is provided, which is given as ageneral composition formula expressed by MmAaBbOoNn:Z, (where element Mis one or more kinds of elements having bivalent valency, element A isone or more kinds of elements having tervalent valency, element B is oneor more kinds of elements having tetravalent valency, O is oxygen, N isnitrogen, and element Z is one or more kinds of activators.), satisfying4.0<(a+b)/m<7.0, n>o, 1.2<a/m≦2.0, 3.0≦b/m≦4.5, 0<o/m≦1.5,n=2/3m+a+4/3b−2/3o, and when the phosphor is irradiated with light witha wavelength range form 300 nm to 500 nm, a peak wavelength in anemission spectrum is in a range from 500 nm to 600 nm.

In a sixty-sixth aspect, the phosphor according to the sixty-fifthaspect is provided, wherein

the element M is one or more kinds of elements selected from the groupconsisting of Mg, Ca, Sr, Ba, and Zn, the element A is one or more kindsof elements selected from the group consisting of Al, Ga, and In, theelement B is Si and/or Ge, and the element Z is one or more kinds ofelements selected from the group consisting of Eu, Ce, Pr, Tb, Yb, andMn.

In a sixty-seventh aspect, the phosphor according to the sixty-fifth orsixty-sixth aspect is provided, wherein the element M is Sr, the elementA is Al, the element B is Si, and the element Z is Ce.

In a sixty-eighth aspect, the phosphor according to any one of thesixty-fifth to sixty-seventh aspect is provided, wherein when thegeneral formula is expressed by MmAaBbOoNn:Zz, the value of z/(m+z),which is a molar ratio of the element M to the element Z, is not lessthan 0.0001 and not more than 0.5.

In a sixty-ninth aspect, the phosphor according to any one of thesixty-fifth to sixty-eighth aspects is provided, wherein when the valueof relative intensity of the maximum peak in the emission spectrum isdefined as P₂₅ when the phosphor is irradiated with a specifiedmonochromatic light in the wavelength range from 300 nm to 500 nm as theexcitation light at 25° C., and the value of the relative intensity ofthe maximum peak is defined as P₁₀₀ when the phosphor is irradiated withthe specified monochromatic light as the excitation light at 100° C.,the relation of P₂₅ and P₁₀₀ is given satisfying (P₂₅−P₁₀₀)/P₂₅×100≦10.

In a seventieth aspect, the phosphor according to any one of thesixty-fifth to sixty-ninth aspects is provided, containing primaryparticles with particle size of 50 μm or less and aggregates in whichthe primary particles agglutinate, wherein an average particle size(D50) of the powdery phosphor containing the primary particles and theaggregates is 1.0 μm or more and 50.0 μm or less.

Advantage of the Invention

The phosphor according to any one of the first to tenth aspects hasemission spectra with a broad peak in the range from green color toyellow color, or yellow color to red color, has a broad flat excitationband in the range from the near ultraviolet/ultraviolet to blue color,and has an improved emission intensity and luminance, and also has anexcellent durability against heat and water.

The phosphor according to the eleventh aspect has a flat excitation bandin the wavelength range from 350 nm to 500 nm. Therefore, even if thereis a slight variation in the emission wavelength of the nearultraviolet/ultraviolet LED and the blue LED used as an excitation lightof the one chip type white LED, disruption of balance in the emissionintensity of each color does not occur, thereby allowing stablemanufacture of the white LED illumination of the same color tone.Therefore, the phosphor of the eleventh aspect has a merit not only inquality but also in manufacturing cost.

The phosphor according to the twelfth aspect has a high emissionintensity and a high luminance even at a high temperature of 200° C.Therefore, even when coated on an LED chip, which is considered tobecome high temperature at light emitting, the emission intensity andthe luminance are not lowered, thereby allowing high luminance one chiptype white LED illumination to be obtained. In addition, there is littlechange in emission characteristics due to heat, and therefore the designof the emission color of the white LED illumination becomes easy.

According to the phosphor of the thirteenth aspect or the fourteenthaspect, the phosphor thus obtained is in a powdery state, therebyallowing the phosphor to be coated on various places as a paste. Inaddition, the phosphor has a particle size of 1.0 μm to 50.0 μm, andmore preferably has a particle size of 1.0 μm to 20.0 μm therebyallowing the coating density to be increased, to make it possible toobtain a coated film with high emission intensity and luminance and lessfluctuation of color.

According to a method of manufacturing the phosphor according to any oneof the fifteenth aspect to twentieth aspect, the phosphor according toany one of the first aspect to twelfth aspect can be manufactured atinexpensive manufacturing cost.

According to the phosphor mixture of any one of the twenty-first aspectto twenty-eighth aspect, when being irradiated with a specifiedexcitation light, the phosphor mixture can efficiently emit light suchas a white color with excellent luminance and color renderingproperties.

According to the phosphor sheet of the twenty-ninth aspect, by combiningthis phosphor sheet and various light emission parts, various lightemission devices can be easily manufactured.

According to the light emission device of any one of the thirtieth tothirty-ninth aspects, a high-efficiency light emission device having adesired emission color and high emission intensity and luminance can beobtained.

The phosphor according to any one of the fortieth to forty-ninth aspectshas emission spectra with a broad peak in the range from green color toyellow color, or yellow color to red color, has a broad flat excitationband in the range from the near ultraviolet/ultraviolet to blue color,and has an improved emission intensity and luminance, and also has anexcellent durability against heat and water.

The phosphor according to the fiftieth aspect has a flat excitation bandin the wavelength range from 350 nm to 550 nm. Therefore, even if thereis a slight variation in the emission wavelength of the nearultraviolet/ultraviolet LED and the blue LED used as an excitation lightof the one chip type white LED, disruption of balance in the emissionintensity of each color does not occur, thereby allowing stablemanufacture of the white LED illumination of the same color tone.Therefore, the phosphor of the fiftieth aspect has a merit not only inquality but also in manufacturing cost.

The phosphor according to the fifty-second aspect has a high emissionintensity and a high luminance even at a high temperature of 200° C.Therefore, even when coated on an LED chip, which is considered tobecome high temperature at light emitting, the emission intensity andthe luminance are not lowered, thereby allowing high luminance one chiptype white LED illumination to be obtained. In addition, there is littlechange in emission characteristics due to heat, and therefore the designof the emission color of the white LED illumination becomes easy.

According to the phosphor of the fifty-third or fifty-forth aspect, thephosphor thus obtained is in a powdery state, thereby allowing thephosphor to be coated on various places as a paste. In addition, thephosphor has a particle size of 1.0 μm to 20.0 μm, thereby allowing thecoating density to be increased, to make it possible to obtain a coatedfilm with high emission intensity and luminance.

According to the phosphor mixture of any one of the fifty-fifth tosixty-forth aspects, when being irradiated with a specified excitationlight, the phosphor mixture efficiently emits light and emits light suchas a white color having excellent luminance and color renderingproperties.

The phosphor according to any one of the sixty-fifth to seventiethaspects is a green phosphor that has an excellent initial emissioncharacteristics by having a flat excitation band in a range from thenear-ultraviolet/ultraviolet to blue color, and a broad emissionspectrum with an emission peak in the vicinity of the wavelength from500 nm to 600 nm which can gain the luminance, and has an excellent heatresistance property and allows almost no deterioration to occur inemission characteristics even under a high temperature environment ascompared to an environment of a room temperature (25° C.).

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be explainedhereunder. However, the present invention is not limited thereto.

A phosphor of the present invention is the phosphor having a matrixcomposition given by a general formula expressed by MmAaBbOoNn:Z. Here,element M is one or more kinds of elements selected from the elementshaving bivalent valency in the phosphor. Element A is one or more kindsof elements having tervalent valency in the phosphor, element B is oneor more kinds of elements having tetravalent valency in the phosphor, Ois oxygen, N is nitrogen, and element Z is an element acting as anactivator in the phosphor and one or more kinds of elements selectedfrom rare earth elements or transition metal elements.

Further, in the phosphor, (a+b)/m is in a range satisfying4.0<(a+b)/m<7.0, a/m is in a range satisfying a/m≧0.5, b/a is in a rangesatisfying b/a>2.5, oxygen and nitrogen has a relation satisfying n>o,and nitrogen is expressed by n=2/3m+a+4/3b−2/3o, and when being excitedby light with a wavelength range of from 300 nm to 500 nm, the phosphorhas an emission spectrum with a peak wavelength from 500 nm to 650 nm.

The phosphor of the present invention having the aforementionedcharacteristics has an emission spectrum with a broad peak in a rangefrom green color to yellow color, or yellow color to red color, and hasa flat excitation band in the broad range from nearultraviolet/ultraviolet to blue color (wavelength range from 300 nm to500 nm), and is capable of obtaining a high-efficiency emission.Therefore, by mixing a phosphor and the phosphor of suitable othercolor, and combining the phosphor thus mixed and an emission part suchas the near ultraviolet/ultraviolet LED and the blue LED and so forth, ahigh-efficiency light emission device having an excellent colorrendering property, a desired emission color and high emission intensityand luminance can be obtained.

The phosphor of the present invention has a stronger emission intensity,high luminance, and a broad peak of the emission spectrum, compared witha silicon nitride-based phosphor (for example see patent document 1) anda sialon-based phosphor (for example, see patent documents 2, 3, and 4),and oxynitride phosphor (for example, see patent documents 5 and 6).Therefore, the white LED illumination with further high luminance can bemanufactured.

The phosphor of the present invention has the same constituent elementas the sialon-based phosphor. However, when expressed by the generalformula MmAaBbOoNn:Z, the sialon-based phosphor meets the formula of(a+b)/m>12/1.5=8. Moreover, as the element M that intrudes into a sialonmatrix structure, only the element with small ionic radius such as Caand Y enters therein, and Sr with larger ionic radius than Ca and Y doesnot enter the matrix structure, and therefore the sialon-based phosphorhas a composition different from the phosphor of the present inventionwherein Sr is indispensable as the element M.

The excitation band of the present invention has a broad range, andtherefore it becomes possible to suppress change in color tone due tovariation in emission elements (blue LED), differently from YAG:Cephosphor. In addition, the phosphor of the present invention has ahigh-efficiency excitation band even in the vicinity of the wavelengthfrom 300 nm to 420 nm, which is an emission wavelength of the nearultraviolet/ultraviolet LED. Accordingly, the phosphor of thisembodiment can also be used as a green color phosphor of the white LEDillumination by combining not only with the blue color emitting LED, butalso with the red color, blue color, and other color phosphors andcombining with the near ultraviolet/ultraviolet emitting LED.Particularly, when the phosphor is irradiated with the excitation lightof monochromatic color in the wavelength range from 350 nm to 500 nm,the phosphor activated by Eu as an activator has a significantly flatexcitation band, wherein the relation is expressed by(P_(H)−P_(L))/P_(H)×100≦20, more preferably expressed by(P_(H)−P_(L))/P_(H)×100≦10, when the peak intensity of a maximum peak isdefined as P_(H) when the phosphor is irradiated with the excitationlight whereby the peak intensity of the maximum peak in the spectrum ofthe light emission obtained by absorbing the excitation light is made tobe largest, and the peak intensity of the maximum peak is defined asP_(L) when the phosphor is irradiated with the excitation light wherebythe peak intensity of the maximum peak in the spectrum of the lightemission obtained by absorbing the excitation light is made to besmallest.

The emission wavelength is different depending on the activator, howeverwhen the phosphor is activated by Ce as a typical activator, thephosphor having the emission spectrum with a broad peak of a half valuewidth of 100 nm or more in a wavelength range from 470 nm to 750 nmwhich is in the range of green color to yellow color, and when activatedby Eu, the phosphor having the emission spectrum with a peak in therange from yellow color to red color can be obtained. Therefore, thephosphor thus activated by Ce can be used by replacing the YAG:Cephosphor, or the ZnS:Cu,Al phosphors presently used as phosphors capableof overcoming problems thereof. Further, the phosphor activated by Eucan be used for the white LED illumination as a different substance fromthe red phosphors such as Ca₂Si₅N₈:Eu, Sr₂Si₅N₈:Eu, Ba₂Si₅N₈:Eu, Ca_(x)(Al, Si)₁₂ (O,N)₁₆:Eu (However, satisfying 0<x≦1.5), CaAl₂Si₄N₈:Eu,CaSiN₂:Eu, CaAlSiN₃:Eu, which have been developed in recent years forimproving color rendering properties of the white LED illumination.

In addition, the phosphor of the present invention has an excellentdurability against heat and water. Although the conventional ZnS:Cu,Alphosphor having the emission spectrum with a peak in the range fromgreen color to yellow color has no problem in regard to the emissionintensity and luminance, problems involved therein are that theZnS:Cu,Al phosphor has no durability, particularly being weak in water,and further, the luminance are largely deteriorated by exposure toultraviolet. Therefore, when the white LED illumination is manufacturedby mixing the ZnS:Cu,Al phosphor and the phosphors of plural colors andby combining with the near ultraviolet/ultraviolet LED, such a white LEDillumination has the problem that when used for a long period of time,particularly the emission intensity and luminance of the ZnS:Cu,Alphosphor are deteriorated, resulting in changing in color tone. Inaddition, when turning on the light of the white LED illumination, theemission intensity and luminance of the ZnS:Cu,Al phosphor aredeteriorated due to the heat or ultraviolet generated from the emissionelement, thereby also deteriorating the luminance of the white LEDillumination accordingly. As a result, the ZnS:Cu,Al phosphor isrequired to adjust phosphor mixed powder in consideration of the changein the emission intensity and luminance due to temperature, making itdifficult to manufacture the white LED illumination with stable quality.However, the phosphor of this embodiment is the phosphor containingnitrogen, having durability, and strong against change in temperatureand moisture in the same way as the silicon nitride phosphor and thesialon-based phosphor, and therefore the white LED illumination havinghigh luminance and excellent durability can be manufactured.

Next, explanation will be given to a case in which the emission withhigh color rendering properties can be obtained by using the phosphor ofthis embodiment.

Preferably, the way of looks of the color is the same as in the case ofusing a reference light. However, the reference light has a white lightsource having uniform intensity of the light over the whole visiblelight region. Meanwhile, the existing white LED illumination lacks inuniformity in the intensity of the light. For example, the intensity ofthe light is high in a certain wavelength region of the visible light,and low in a certain wavelength region. Therefore, in the wavelengthregion where the intensity of the light is insufficient, colorreproducing properties are deteriorated, and the color renderingproperties are deteriorated.

After all, in order to obtain the emission with high color renderingproperties, the phosphor used for the white LED illumination needs tohave an emission spectrum with a broad peak, and the phosphor needs tohave a sufficient emission intensity. With the phosphor of the presentinvention having the aforementioned matrix composition, the phosphorhaving a high emission intensity and luminance in the range from greencolor to yellow color, or from yellow color to red color, and having anemission spectrum with a broad peak of not less than 80 nm half valuewidth can be obtained by changing the kind of the constituent elementand the kind of the activator.

Detailed reason remains unknown for the fact that the phosphor of thepresent invention has the emission spectrum with a broad peak in therange from the green color to yellow color and from yellow color to redcolor, has the flat excitation band in the wavelength range from thenear ultraviolet/ultraviolet to blue color, and is capable of emittinglight with high efficiency. However, it can be considered as follows.

First, it can be considered that in the general formula MmAaBbOoNn:Z ofthe phosphor according to the present invention, when the values of m,a, b, o, and n are in the range of 4.0<(a+b)/m<7.0, a/m≧0.5, b/a>2.5,n>o, n=2/3m+a+4/3b−2/3o, the activator can exist regularly in a crystalstructure of the phosphor, an excitation energy used for emitting lightcan be efficiently transferred, and an emission efficiency is therebyimproved.

Further, with the aforementioned constituent of the phosphor, it can beconsidered that the phosphor has chemically stable composition,therefore an impurity phase not contributing to emitting light is hardlygenerated in the phosphor, and the reduction in the emission intensityis thereby suppressed. Namely, it can be considered that when pluralimpurity phases are generated, a phosphor amount per unit area isreduced, and further the impurity phase thus generated absorbs theexcitation light and the light generated from the phosphor, thereforethe emission efficiency of the phosphor is deteriorated, and the highemission intensity can not be obtained.

The aforementioned consideration is supported by the fact that when thevalues of m, a, b, o, and n are in the aforementioned range in an X-raydiffraction measurement for the phosphor after firing, an X-raydiffraction peak due to the impurity phase of an unreacted raw materialsuch as AlN, and Si₃N₄, and the X-ray diffraction peak due to theimpurity phase different from the phase contributing to emitting lightare not confirmed, or even when confirmed, a significantly lowdiffraction intensity is observed. Meanwhile, when the values of m, a,b, o, and n are outside the aforementioned range, a remarkable X-raydiffraction peak of the phase of the AlN Si₃N₄ and the phase differentfrom the phase contributing to emitting light is confirmed. Therefore,it can be considered that the characteristic that the X-ray diffractionpeak due to the aforementioned impurity phase is not observed in theX-ray diffraction pattern for the phosphor after firing, shows that thephosphor to be measured has a high emission intensity and a flatexcitation band over the range from the near ultraviolet/ultravioletcolor to blue color.

In the phosphor of the present invention, the general formula is givenas MmAaBbOoNn:Z, where preferably the values of m, a, b, o, and n aregiven satisfying 4.0<(a+b)/m<7.0, a/m≦0.5, b/a>2.5, n>o,n=2/3m+a+4/3b−2/3o, further preferably satisfying 0.5≦a/m≦2.0,3.0<b/m<7.0, 0<o/m≦4.0, and still further preferably 0.8≦a/m≦1.5,3.0<b/m<6.0, 0<o/m≦3.0. This is because in a case of a/m=0, oxygen andSi contained in the raw material are excessively reacted during firing,resulting in being vitrified, thus making it impossible to obtainexcellent emission characteristics and powdery phosphor.

Meanwhile, in a case of a/m≠0, Al is solid-solubilized and a meltingpoint of a generated compound becomes extremely high. Therefore, evenwhen firing is performed, a vitrification does not occur, and a powderyphosphor can be obtained after firing. Accordingly, it is preferable toset the value of a/m at 0.5 or more.

Further, in a case of 1.1<a/m, the emission characteristics under anenvironment of a high temperature are hardly deteriorated, as comparedto a case of the aforementioned range. Further, even when the emissionintensity (25° C.) before increasing the temperature up to 300° C. andthe emission intensity after holding for 5.0 minutes at 300° C. andcooling down to a room temperature (25° C.) again are compared, anexcellent heat resistance property, i.e., that the emission intensityafter the cooling is not deteriorated as compared to an emissionintensity of before increasing the temperature, is expressed.

In a case of a/m≦2.0, a site of the element B to be replaced with theelement A is prevented from being excessive, thus making it possible toprevent the emission efficiency from deteriorating due to a variation ofmanufacturing conditions, and suppress the deterioration of the emissioncharacteristics even when this phosphor is placed under a hightemperature environment. Further, with this constituent, an unreactedAlN generation can be suppressed, and the deterioration of an initialemission intensity due to this unreacted AlN can be prevented. Inaddition, if the value of “b” is larger than the value of “a”, thesintering is suppressed and a powdery phosphor can be easily obtainedafter firing. Therefore, it is preferable to set the range of b/m in therange of 3.0≦b/m≦6.0 which is larger than a/m, and is more preferable toset it in the range of 3.5≦b/m≦4.5.

Preferably, the phosphor of the present invention contains oxygen,although satisfying n>o. An appropriate content of the oxygen is changeddepending on the molar ratio of Al and Si in the phosphor. However, byoptimizing this oxygen content, the initial emission characteristic (25°C.) of the phosphor is improved and also the phosphor, whose emissioncharacteristic is hardly deteriorated even under a high temperatureenvironment as compared to a case of a room temperature (25° C.), can beobtained. This is because even if trying to improve the temperaturecharacteristic, a crystal structure is deviated from the structuresuitable for light emission even when the Si site is simply replacedwith Al, because the ionic radius of the Al is different from that ofSi. Further, Si is tetravalent valency while Al is tervalent valency,thus involving a problem that the valency in a crystal becomes unstable.However, when a part of an N sites is replaced with O in accordance withan amount of Al for replacing the Si site, the crystal structuresuitable for light emission can be obtained and further, the valency ofan entire body of a matrix crystal structure can be set to stable zero,and therefore it can be considered that excellent emissioncharacteristics can be exhibited. Here, a preferable range of an amountof oxygen is 0<o/m≦4.0, and when oxygen content in the phosphor afterfiring is analyzed, a sufficiently practical phosphor with excellentemission characteristics and suppressing vitrification is realized,provided that the oxygen content is in a range of more than 0.5 wt % toless than 8.1 wt % relative to amass of the phosphor. Further, when theamount of the oxygen is in a range of 0<o/m≦3.0 and more preferably in arange of 0<o/m≦1.5, i.e. in a range of more than 0.5 wt % to less than5.0 wt %, the emission intensity is further improved and this ispreferable.

The reason for a slightly different value between the value of ocalculated by a result of composition analysis, and the value of ocalculated by the mixing ratio of the raw material to be used, which arecompared with each other, is considered to be that the oxygen initiallycontained in the raw material and the oxygen adsorbed to the surface,the oxygen mixed therein by oxidization of the surface of the rawmaterial at measuring, mixing, and firing the raw material, and furtherthe oxygen adsorbed on the surface of the phosphor after firing, are nottaken into consideration. In addition, the reason is considered in sucha way that when firing is performed in an atmosphere containing nitrogengas and/or ammonia gas, the raw material is nitrided during firing anddeviation occurs in the amount of o and amount of n.

Further, in the phosphor having the composition expressed by theaforementioned general formula MmAaBbOoNn:Z, element M is one or morekinds of elements having+II valency, element A is one or more kinds ofelements having+III valency, element B is one or more kinds of elementshaving+IV valency, and nitrogen is one or more kinds of elementshaving−III valency. Therefore, the values of m, a, b, o, and n are thecomposition expressed by n=2/3m+a+4/3b−2/3o, and the value obtained byadding the valency of each element becomes zero, and preferably thephosphor thus described serves as a further stable compound.Particularly, in this phosphor, when a/m is in a range of 1.1<a/m≦1.5,b/m is in a range of 3.5≦b/m≦4.5, and o/m is in a range of 0<o/m≦1.5,the emission characteristics and the heat resistance are furtherimproved and this is preferable constituent. In any case, slightdeviation in composition from a composition formula showing thecomposition of the phosphor is allowable.

Meanwhile, preferably the element M is one or more kinds of elementsselected from a group consisting of Mg, Ca, Sr, Ba, Zn, and rare earthelements having bivalent valency, further preferably is one or morekinds of elements selected from a group consisting of Mg, Ca, Sr, Ba,and Zn, and most preferably is Sr. Further, 90% or more of Sr iscontained as the element M, and a part of the element M may by replacedby the aforementioned other elements.

Preferably the element A is one or more kinds of elements selected froma group consisting of Al, Ga, In, Tl, Y, Sc, P, As, Sb, and Bi, furtherpreferably is one or more kinds of elements selected from a groupconsisting of Al, Ga, and In, and most preferably is Al. Further, 90% ormore of Al is contained as the element A, and a part of the element Amay be replaced by the aforementioned other elements. In regard to theAl, preferably AlN, which is a nitride, is used as a generalheat-transfer material and a structural material, and easily availableat an inexpensive cost, and brings small environmental loading, and thisis preferable.

Preferably the element B is one or more kinds of elements selected froma group consisting of Si, Ge, Sn, Ti, Hf, Mo, W, Cr, Pb, and Zr, furtherpreferably is Si and/or Ge, and most preferably is Si. Further, 90% ormore of Si is contained as the element B, and a part of the element Bmay be replaced by the aforementioned other element. In regard to theSi, preferably Si₃N₄, which is a nitride, is used as a generalheat-transfer material and a structural material, and easily availableat an inexpensive cost, and brings small environmental loading, and thisis preferable.

The element Z is one or more kinds of elements selected from rare earthelements or transition elements mixed in the form of replacing a part ofthe element M in the matrix structure of the phosphor. From theviewpoint of exerting a sufficient color rendering property for variouslight sources including the white LED illumination using the phosphor ofthe present invention, it is preferable for the phosphor to have a broadhalf width value of the peak in the emission spectrum. From thisviewpoint, preferably, the element Z is one or more kinds of elementsselected from a group consisting of Eu, Mn, Ce, Tb, Pr, and Yb. Amongthese elements, when Ce is used as the element Z, the phosphor shows theemission spectrum with broad and high in emission intensity in the rangefrom green color to yellow color, and therefore Ce is preferable as anactivator of each kind of light source including the white LEDillumination.

Although a silicon nitride-based phosphor, a sialon-based phosphor, andoxynitride phosphor of patent documents 1 to 6 proposed heretofore emitlight from green color to yellow color by activating with Ce, theemission intensity is significantly deteriorated compared with a case inwhich the same matrix is activated by Eu, thus making it impossible tobe practically used. However, the present invention provides thephosphor of a proper composition to obtain the emission spectrum with apeak in a broad range and high in emission intensity, and therefore iscapable of obtaining the emission intensity of not less than 1.5 timesthat of the phosphor of each patent document, having the characteristicof sufficiently being put to practical use. Further, when the white LEDillumination is manufactured by the near ultraviolet/ultraviolet LED,the phosphor of the present invention has a significantly broad peak inthe emission spectrum compared to ZnS:Cu,Al used as a green phosphor,and therefore the white LED illumination improved in efficiency andexcellent in color rendering property can be manufactured. Further, anoteworthy point is that even when the matrix is activated by Eu, theemission intensity is not deteriorated, showing the emission spectrumwith a peak in a broad range and high in the emission intensity fromyellow color to red color.

Moreover, by selecting the element Z, the peak wavelength of lightemission performed by the phosphor of the present invention can bechanged, and also by co-activating the different kind of element Z, thepeak wavelength can be changed and further by a sensitization action,the emission intensity and the luminance can be improved.

An amount of the element Z to be added is preferably in the range of notless than 0.0001 and not more than 0.50 in a molar ratio z/(m+z) of theelement M and the element Z as an activator, when the general formula ofthe phosphor of the present invention is expressed by the generalformula MmAaBbOoNn:Zz (satisfying 4.0<(a+b)/m<7.0, a/m≧0.5, b/a>2.5,n>o, n=2/3m+a+4/3b−2/3o). When the molar ratio z/(m+z) of the element Mand the element Z is in the aforementioned range, thereby preventing thedeterioration in the emission efficiency by concentration quenchinggenerated due to an excessive content of the activator (element Z), andmeanwhile, the element contributing emitting light becomes deficient dueto too small content of the activator (element Z), and the emissionefficiency is thereby prevented from deteriorating. Further, it ispreferable to set the value of the z/(m+z) within the range of not lessthan 0.001 and not more than 0.30. However, an optimal value of therange of the value of z/(m+z) is slightly fluctuated by the kind of theactivator (element Z) and the kind of the element M. Further, bycontrolling the amount of the activator (element Z) to be added, thepeak wavelength of the light emission of the phosphor can be shifted andset, which is useful for adjusting the luminance in the light sourcethus obtained.

In addition, when Sr was selected as the element M, and Al was selectedas the element A, Si was selected as the element B, and Ce was selectedas the element Z, satisfying 4.0<(a+b)/m<7.0, 0.5≦a/m≦2.0, 3.0<b/m≦7.0,0<o/m≦4.0, n=2/3m+a+4/3b−2/3o, the weight ratio of the elementconstituting the aforementioned phosphor was obtained by elementalanalysis, such as Sr of 19.5 wt % to 29.5 wt %, Al of 5.0 wt % to 16.8wt % of 0.5 wt % to 8.1 wt %, N of 22.6 wt % to 32.0 wt %, and Ce ofmore than 0.0 to 3.5 wt % or less. However, error of ±1.0 wt % for Srand Al is estimated and the remaining weights are Si and other elements.Note that from the viewpoint of preventing the deterioration in theemission intensity of the phosphor, the concentration of each element ofFe, Ni, and Co in the phosphor is preferably 100 PPM or less.

When the phosphor is irradiated with one or more kinds of monochromaticlights or mixed light of the monochromatic lights having the wavelengthrange from 350 nm to 500 nm as an excitation light, the peak wavelengthof the emission spectrum was in the range from 500 to 600 nm. At thistime, the phosphor exhibited a sufficient emission intensity andexhibited a preferable emission characteristic of having a chromaticity(x, y) of the emission spectrum, with x in the range from 0.3000 to0.4500, and y in the range from 0.5000 to 0.6000.

In addition, when Sr was selected as the element M, and Al was selectedas the element A, Si was selected as the element B, and Eu was selectedas the element Z, satisfying 4.0<(a+b)/m<7.0, 0.5≦a/m≦2.0, 3.0<b/m<7.0,0<o/m≦4.0, n=2/3m+a+4/3b−2/3o, the weight ratio of the elementconstituting the aforementioned phosphor was obtained by elementalanalysis, such as Sr of 19.5 wt % to 29.5 wt %, Al of 5.0 wt % to 16.8wt %, 0 of 0.5 wt % to 8.1%, N of 22.6 wt % to 32.0 wt %, and Eu of morethan 0.0 to 3.5 wt % or less. However, error of ±1.0 wt % for Sr and Alis estimated and the remaining weights are Si and other elements.

Note that from the viewpoint of preventing the deterioration of theemission intensity of the phosphor, the concentration of each element ofFe, Ni, and Co in the phosphor is preferably 100 PPM or less. Inaddition, when the phosphor is irradiated with one or more kinds ofmonochromatic lights or mixed light of the monochromatic lights havingthe wavelength range from 350 nm to 500 nm as an excitation light, thepeak wavelength of the emission spectrum was in the range from 550 to650 nm. At this time, the phosphor exhibited a sufficient emissionintensity and exhibited a preferable emission characteristic of having achromaticity (x, y) of the emission spectrum, with x in the range from0.4500 to 0.6000, and y in the range from 0.3500 to 0.5000.

When a powder X-ray diffraction pattern measurement by Co Kα ray isperformed for the phosphor according to the present invention, thefollowing characteristic is observed.

A product phase contained in the phosphor of the present invention hascharacteristic peaks in a Bragg angle (2θ) ranges of 12.5 to 13.5°, 17.0to 18.0°, 21.0 to 22.0°, 22.5 to 23.5°, 26.5 to 27.5°, 28.5 to 29.5°,34.0 to 35.0°, 35.5 to 36.5°, 36.5 to 37.5°, 41.0 to 42.0°, 42.0 to43.0°, 56.5 to 57.5°, and 66.0 to 67.0°. From this diffraction pattern,it appears that the phosphor has a main production phase with a crystalsystem of a orthorhombic crystal or a monoclinic crystal. The crystalsystem with a sialon as a matrix is generally a hexagonal crystal, andtherefore the phosphor according to the present invention is consideredto have the crystal system different from a publicly known phosphor withsialon as the matrix.

Next, the temperature characteristic of the phosphor of the presentinvention will be explained. In some cases, the phosphor is used, notonly as the white LED illumination, under high temperature environment.Accordingly, when the phosphor whose emission intensity is deterioratedin association with an increase of the temperature, and whose emissioncharacteristic is deteriorated in association with thermaldeterioration, such a phosphor is not preferable.

The phosphor according to the present invention exhibits excellenttemperature characteristics and heat resistance, and when the value ofrelative intensity of the maximum peak in the emission spectrum isdefined as P₂₅ when the phosphor is irradiated with a specifiedmonochromatic light or mixed light of the monochromatic lights in thewavelength range from 300 nm to 500 nm as the excitation light at 25°C., and the value of the relative intensity of the maximum peak isdefined as P₂₀₀ when the phosphor is irradiated with the excitationlight at 200° C., the relation of P₂₅ and P₂₀₀ is given satisfying(P₂₅−P₂₀₀)/P₂₅×100≦35, thus showing excellent emission characteristicseven under a high temperature environment. Further preferably, when thevalue of the relative intensity of the maximum peak at 100° C. isdefined to be P₁₀₀, the relation of P₂₅ and P₁₀₀ is expressed by(P₂₅−P₁₀₀)/P₂₅100≦10.0.

In addition, when a heat generation temperature of the LED was examinedby the inventors of the present invention, it was found that althoughthe temperature was about 50° C. in a small-sized and small current typechip, heat generation occurs up to 80° C. when a large-sized and largecurrent type chip is used to obtain further strong emission. Further, ina case of the white LED, it was found that the generated heat wasaccumulated by sealing of the chip by resin and a lead frame structure,and the temperature of the resin or the phosphor mixture part becameabout 100° C. and 200° C. at maximum. Namely, when the relation of P₂₅and P₂₀₀ satisfies (P₂₅−P₂₀₀)/P₂₅×100≦35, further preferably(P₂₅−P₁₀₀)/P₂₅×100≦10.0, a color shift of the emission due to this heatgeneration can be suppressed to a level not involving problem as thewhite LED illumination, even if the heat generation that occurs withlighting the LED, being an emission light source, for a long period oftime, is accumulated.

The phosphor according to the present invention has high temperaturematerials, as a matrix, such as nitride and oxynitride with excellentdurability at high temperature generated from AlN and Si₃N₄, and atetrahedral (SiN₄) is assembled into a network, thus producing adifferent structure from the conventional nitride and oxynitridephosphor, and an Al replacement amount of the Si site and an Oreplacement amount of the N site are optimized. Therefore, an extremelystable structure against heat is realized, thus exhibiting an excellenttemperature characteristic. Further, in the phosphor according to theconventional technique, when used once at a high temperatureenvironment, there is a problem that the emission intensity becomeslower than the emission intensity before being used under a hightemperature environment even when being returned to a room temperature.However, the phosphor of the present invention can solve this problem.

In addition, since the light emission device of the present inventionhas excellent temperature characteristics, the phosphor hardly allowingthe color shift to occur even when the temperature of the light emissiondevice is increased, can be manufactured. The phosphor of the presentinvention has the emission spectrum with a peak in the range from greencolor to yellow color, having a broad peak form, and therefore it ispreferable as phosphor for the white LED illumination from the viewpointof color rendering properties. Further, the excitation band is flat inthe broad range of near ultraviolet/ultraviolet to blue green color(wavelength range from 300 to 500 nm). Therefore, the phosphor of thepresent invention provides a state close to a maximum emission intensityeven in case of the white LED illumination of a system to obtain whitecolor by utilizing a complementary relation between a blue lightemission of the high luminance blue LED (in the vicinity of thewavelength from 420 to 480 nm) and yellow light emission of the phosphorproposed as the one chip type white LED illumination, or the case of thewhite LED illumination of the system obtaining white color by utilizingthe mixed state of colors of the light obtained from the phosphors of R,G, and B, and other colors by combining the LED emitting light of nearultraviolet/ultraviolet (in the vicinity of the wavelength of 300 to 420nm), red color (R) emitting phosphor excited by the nearultraviolet/ultraviolet light generated from the LED, green color (G)emitting phosphor, and blue color (B) emitting phosphor. Namely, bycombining the emission part emitting light from the nearultraviolet/ultraviolet to blue color and the phosphor, the white lightsource and the white LED illumination with high output and improvedcolor rendering properties, and further an illumination unit using thesame can be obtained.

By forming the phosphor of the present invention in a powdery state, thephosphor can be easily applied to various light sources including thewhite LED illumination. Here, when the phosphor is used in a powderystate, preferably the phosphor contains primary particles with particlesize of 50 μm or less and aggregates in which the primary particlesagglutinate, wherein the an average particle size (D50) of the powderyphosphor containing the primary particles and the aggregates is not lessthan 1.0 μm and not more than 50.0 μm and more preferably is not lessthan 1.0 μm and not more than 20.0 μm. The reason is considered asfollows:

when the average particle size is 50 μm or less, it can be easilypulverized thereafter;

since the emission occurs mainly on the surface of a particle in thephosphor powder, a surface area per unit weight of powder can be securedand the deterioration of the luminance is thereby prevented when theaverage particle size is not more than 50.0 μm and more preferably notless than 20.0 μm; and when the powder is formed into a paste, which isthen applied on a light emitter element, density of the powder can beincreased, thus making it possible to prevent fluctuation of color anddeterioration of luminance. Also, according to the study of the presentinventors, although detailed reason was unknown, it was found thatpreferably the average particle size is larger than 1.0 μm from theviewpoint of the emission efficiency of the phosphor powder. Asdescribed above, the average particle size of the powder in the phosphorof the present invention is not less than 1.0 μm and not more than 50μm, and further preferably is not more than 20 μm. The average particlesize (D50) specified here is the value measured by a LS230 (laserdiffraction dispersion method) by Beckman Coulter, Inc. The value of aspecific surface area (BET) is also changed with the change of theparticle size, and therefore from this viewpoint, the value of thespecific surface area is preferably not less than 0.05 m²/g and not morethan 5.00 m²/g.

Next, in regard to the manufacturing method of the phosphor of thepresent invention, manufacture of Sr₂Al₂Si₉O₂N₁₄:Ce (whereinCe/(Sr+Ce)=0.030) will be explained as an example. Note that the z/(m+z)and Ce/(Sr+Ce) are the same meaning.

Generally, in many cases, the phosphors are manufactured by asolid-phase reaction, and the phosphor of the present invention can bealso obtained by the solid-phase reaction. However, the manufacturingmethod is not limited thereto. Each raw material of the element M, theelement A, the element B may be obtained by the raw materialcommercially available, such as nitride, oxide, carbonate, hydroxide,and basic carbonate. However, higher purity is more preferable, andpreferably, the raw material of 2N or more, further preferably the rawmaterial of 3N or more is prepared. The particle size of each particleof the raw material is preferably a fine particle, in terms ofaccelerating the reaction. However, the particle size and a form of thephosphor obtained are changed, depending on the particle size and theform of the raw material. Therefore, the raw material of the nitride andso forth having an approximate particle size in accordance with theparticle size and the form required for the phosphor finally obtainedmay be prepared. However, preferably the raw material with particle sizeof 50 μm or less, further preferably 0.1 μm or more and 10.0 μm or lessmay be used. As the raw material of the element Z also, the commerciallyavailable nitride, oxide, carbonate, hydroxide, basic carbonate, orsimple metal is preferable. Of course, the higher purity of each rawmaterial is more preferable, and the raw material of 2N or more, andfurther preferably the raw material of 3N or more are prepared.Particularly, using the carbonate as the raw material of the element Mis preferable because an effect of flux (reaction accelerator) can beobtained without adding a compound as flux composed of the element notcontained in the composition element of the phosphor of this embodiment.

When manufacturing Sr₂Al₂Si₉O₂N₁₄:Ce (where Ce/(Sr+Ce)=0.030), forexample, preferably SrCO₃ (3N), AlN (3N), Si₃N₄ (3N) are respectivelyprepared as the raw materials of the element M, the element A, theelement B, and CeO₂(3N) is prepared as the element Z. Then, severalpoints are examined in consideration of a deviation generated between amixing (charging) composition of raw materials and the composition afterfiring, and a mixing charging composition, whereby a target compositioncan be obtained after firing, is obtained. In a raw material mixingstep, 0.970 mol of SrCO₃, 1.0 mol of AlN, 4.5/3 mol of Si₃N₄, and 0.030mol of CeO₂ of the raw materials are weighed and mixed so that a molarratio of each element after firing in this case isSr:Al:Si:Ce=0.970:1:4.5:0.030. The carbonate is used as a Sr rawmaterial. This is because when the raw material with low melting pointsuch as carbonate is used, the raw material itself serves as flux toaccelerate the reaction and improve the emission characteristic, whilean oxide raw material has a high melting point and the effect of fluxcan not be expected. In addition, when the oxide is used as the rawmaterial, another substance may be added as the flux. However, in thiscase, it must be careful that the flux becomes impurity, and there is apossibility that the characteristic of the phosphor is deteriorated.Therefore, it must be careful to select the flux. For example, chloride,fluoride, oxide, and nitride are preferable, and SrF₂, BaF₂, AlF₃,SrCl₂, BaCl₂, AlCl₃, Al₂O₃, Ga₂O₃, In₂O₃, SiO₂, GeO₂, SrO, BaO, Ga₃N₂,Sr₃N₂, Ba₃N₂, GaN, InN, and BN, etc., are exemplified.

The weighing and mixing may be performed in an atmospheric air. However,the nitrides in each raw material element are easy to be influenced byhumidity, and therefore it is convenient to operate in a glove box underan inactive atmosphere where humidity is sufficiently removed. Either ofa dry system or a wet system may be used as a mixing system. However,the raw material is decomposed when pure water is used as a solvent ofthe wet mixing. Therefore, a suitable organic solvent must be selected.A usual device such as a ball mill and a mortar may be used.

The raw material thus completed in mixing is put in a crucible, andretained and fired, while distributing an atmosphere gas into a firingfurnace at 1400° C. or more, preferably 1500° C. or more or 1600° C. ormore, further preferably not less than 1700° C. and not more than 2000°C. for 30 minutes or more. If a firing temperature is 1400° C. or more,it is difficult to generate the impurity phase emitting blue light whenbeing excited by ultraviolet rays, and further, the solid-phase reactionis preferably advanced and the phosphor excellent in emissioncharacteristic can be obtained. Moreover, if the firing temperature is2000° C. or less, preferably 1850° C. or less, excessive sintering andmelting can be prevented from occurring. Note that higher firingtemperature allows the solid-phase reaction to be rapidly advanced, anda retaining time can thereby be shortened. Meanwhile, even when thefiring temperature is low, a target emission characteristic can beobtained by firing at the temperature for a long time. However, longerfiring time allows a particle growth to be advanced, and a particle formbecomes large. Therefore, the firing time may be set in accordance witha target particle size.

As an atmosphere gas to be distributed into a firing furnace, any one ofthe inactive gas such as rare gas, ammonia, mixed gas of ammonia andnitrogen, or mixed gas of nitrogen and hydrogen may be used. However,when the oxygen is contained in this atmosphere gas, oxidation reactionof a phosphor particle occurs. Therefore, the oxygen contained as theimpurity is preferably as little as possible and for example, ispreferably 100 PPM or less. Further, when the humidity is contained inthe atmosphere gas, in the same way as the oxygen, the oxidationreaction of the phosphor particle occurs during firing. Therefore, thehumidity contained as the impurity is preferably as little as possibleand for example, is preferably 100 PPM or less. Here, when a single gasis used as the atmosphere gas, nitrogen gas is preferable. Althoughfiring by a single use of the ammonia gas is also possible, the ammoniagas is expensive in terms of cost, and is a corrosive gas, and thereforea special processing is needed in devices and an exhaustion methodduring a low temperature. Accordingly, when the ammonia is used, theammonia is preferably used at a low concentration, for example, by usingthe mixed gas of ammonia and nitrogen. For example, when the mixed gasof nitrogen gas and ammonia is used, it is preferable to prepare 80% ormore of nitrogen and 20% or less of ammonia. In addition, when the mixedgas of nitrogen and other gas is used, a partial pressure of thenitrogen in the atmosphere gas is decreased when a gas concentrationother than nitrogen is increased. Therefore, from the viewpoint ofaccelerating the nitridation reaction of the phosphor, the inactive orreduction gas containing 80% or more of nitrogen is preferably used.

In addition, preferably during firing, preferably the aforementioned gasatmosphere flows with a flow rate of 0.1 ml/min, for example. This isbecause although during firing the raw material of phosphors, a gasgenerates from the raw material, by flowing the atmosphere containingone or more kinds of gases selected from the aforementioned nitrogen,inactive gas such as rare gas, ammonia gas, a mixed gas of ammonia gasand nitrogen, and a mixed gas of nitrogen and hydrogen, it is preventedthat the gas generated from the raw material is filled in the furnace tohave influence on the reaction, resulting in the deterioration in theemission characteristic of the phosphor. Particularly, when the rawmaterial decomposing to the oxide at high temperature such as thecarbonate, the hydroxide, and the basic carbonate are used for the rawmaterial, a large amount of gas is generated. Therefore, it ispreferable to make the gas flow in a firing furnace and exhaust the gasthus generated.

Meanwhile, in a step of firing raw materials of phosphor inmanufacturing the phosphor, pressure in the firing furnace is set in apressurized state so as not to allow the oxygen in the atmospheric airto mix in the furnace. However, when this pressurized state exceeds 1.0MPa (in the present invention, in-furnace pressure means a pressurizedamount from the atmospheric pressure), a special pressure resistantdesign is required for designing a furnace facility. Therefore, inconsideration of productivity, 1.0 MPa or less of pressurization ispreferable. In addition, when this pressurization is increased,sintering between particles may be excessively advanced, thus making itdifficult to pulverize after firing. Therefore, in-furnace pressureduring firing is preferably 1.0 MPa or less, more preferably 0.5 MPa orless, and further preferably 0.001 MPa or more and 0.1 MPa or less.

Note that an Al₂O₃ crucible, a Si₃N₄ crucible, an AlN crucible, a sialoncrucible, a C (carbon) crucible, and a BN (boron nitride) crucible orthe like which can be used in the aforementioned gas atmosphere may beused as a crucible. Preferably the BN crucible is used, since intrusionof impurities can be averted.

In the present invention, preferably the raw material is fired in astate of powder. In a general solid-phase reaction, by dispersion ofatoms in contact points of the raw materials, the reaction is promoted.This is taken into consideration, and in many cases, the raw material isformed into a pellet and fired, to accelerate the reaction uniformlyover the entire raw materials. However, in a case of the raw material ofthe phosphor of the present invention, the raw material is fired in apowder state, easy to pulverize after firing, and a primary particle isformed in an ideal spherical shape. Thus, the fired product is easy tobe treated as a powder. Further, when carbonate, hydroxide, and basiccarbonate are used as raw materials, CO₂ gas is generated by thedecomposition of the raw material during firing. However, in case of theraw material in a powder state, the gas would fully come out, andtherefore from the viewpoint of not having a negative influence on theemission characteristic, this is a preferable constituent.

After completing the firing, an object thus fired is taken out from thecrucible, pulverizing means such as the mortar and the ball mill is usedto pulverize the raw material to a predetermined average size, and thephosphor of the composition expressed by Sr₂Al₂Si₉O₂N₁₄:Ce (whereCe/(Sr+Ce)=0.030) can be manufactured. The phosphor thus obtained isthen subjected to washing, classifying, surface treatment, and heattreatment as needed. As a washing method, washing in an acidic solutionusing hydrofluoric acid, hydrochloric acid, sulfuric acid, and nitricacid is preferable, because metal atoms such as Fe adhered to thesurface of particles and raw material particles remained in an unreactedstate are dissolved. An amount of Fe, Ni, and Co contained in theobtained phosphor is preferably 100 PPM or less.

When other element is used as the element M, the element A, the elementB, and the element Z, and when an amount of activation of Ce, which isthe activator, is changed, by adjusting a blending amount of each rawmaterial at mixing to a predetermined composition ratio, the phosphorcan be manufactured by the same manufacturing method as theaforementioned method.

Next, the phosphor mixture according to the present invention will beexplained. The phosphor mixture of the present invention includes theaforementioned green phosphor, one or more kinds of blue phosphorshaving the emission spectrum with a maximum peak in the wavelength rangefrom 420 nm to 500 nm when being excited by the excitation light, beingone or more kinds of monochromatic lights or continuous lights havingthe wavelength range from 300 nm to 500 nm, and/or one or more kinds ofred phosphors having the emission spectrum with a maximum peak in thewavelength range from 590 nm to 680 nm when being excited by theexcitation light, being one or more kinds of monochromatic lights orcontinuous lights having the wavelength range from 300 nm to 500 nm. Thephosphor mixture having this constituent has a spectrum with a uniformlight density over the whole visible light region, by mixing lights ofvarious wavelengths, which is the phosphor mixture having excellentcolor rendering properties during emitting light, whereby the emissiondevice particularly excellent in emission efficiency with high luminancecan be obtained.

Explanation will be given to the red phosphor having the emissionspectrum with a maximum peak in the wavelength range from 590 nm to 680nm, included in the phosphor mixture of the present invention.

A publicly-known red phosphor having excitation characteristics andemission characteristics can be used for this red phosphor.

First, there is provided the red phosphor performing red color emissionwith high luminance having the emission spectrum with a maximum peak inthe wavelength range from 590 nm to 680 nm, with high efficiency whenbeing irradiated with the light in the wavelength range from 250 nm to500 nm and further preferably the wavelength range from 300 nm to 500 nmas the excitation light. Further, a half value width of this emissionspectrum is preferably 50 nm or more.

As an example of this red phosphor, there is a phosphor which is givenby a general composition formula expressed by MmAaBbOoNn:Z, (where theelement M is one or more kinds of elements selected from the groupconsisting of Ca, Mg, Sr, Ba, and Zn, the element A is one or more kindsof elements selected from the group consisting of Al, Ga, and In, theelement B is one or more kinds of elements selected from the groupconsisting of Si, Ge and Sn, and the element Z is one or more kinds ofelements selected from rare earth elements and transition metalelements, satisfying n=2/3m+a+4/3b−2/3o, m=1, a≧0, b≧m, n>o, o≧0). Forexample, the red phosphor such as (Ca,Sr,Ba)₂Si₅N₈:Eu disclosed in thepatent document 1, and 2.75SrO.Si₃N₄:Eu disclosed in JP patentapplication No. 2004-145718 can be used. Further preferably, from thisviewpoint, the red phosphor expressed by the composition formula ofCaAlSiN₃:Eu is preferable.

Next, explanation will be given to the blue phosphor having the emissionspectrum with a maximum peak in the wavelength range from 420 nm to 500nm, included in the phosphor mixture of the present invention.

A publicly-known blue phosphor having excitation characteristics andemission characteristics as will be explained hereunder can be used forthis blue phosphor.

First, there is provided the blue phosphor performing blue coloremission with high luminance having the emission spectrum with a maximumpeak in the wavelength range from 420 nm to 500 nm, with high efficiencywhen being irradiated with the light in the wavelength range from 250 nmto 420 nm and further preferably the wavelength range from 300 nm to 420nm as the excitation light. Further, a half value width of this emissionspectrum is preferably 30 nm or more, and further preferably 50 nm ormore

BAM:Eu (BaMgAl₁₀O₁₇:Eu), (Sr, Ca, Ba, mg)₁₀(PO₄)₆Cl₂:Eu, orSrAl_(x)Si_(6−X)O_(1+X)N_(8−x):Eu (0≦x≦2), etc., can be given as anexample of the blue phosphor having the excitation characteristics andemission characteristics.

Next, a method of obtaining the phosphor mixture of the presentinvention will be explained.

The green phosphor, the red phosphor and/or the blue phosphormanufactured by the aforementioned method are mixed, and the phosphormixture according to the present invention is manufactured. By setting amixing ratio of each phosphor, the correlated color temperature of theobtained emission spectrum can be set at a desired value between 10000Kto 2000K, when this phosphor mixture is irradiated with the excitationlight in the wavelength range from 300 nm to 500 nm. Here, from theviewpoint of an illumination light source, the correlated colortemperature is preferably set at a desired value between 7000K to 2500K.Specifically, each emission spectrum for a target excitation light ofthe phosphor of each color is measured, the obtained emission spectrumis synthesized by simulation, and the mixing ratio for obtaining adesired correlated color temperature may be obtained.

Regarding an evaluation method of the emission efficiency of theobtained phosphor mixture, the phosphor mixture is actually applied onthe emission element together with resin and the emission efficiency maybe compared in a state that the element is allowed to emit light.However, this is not a uniform evaluation, because the variation ofefficiency of the light emitting element itself or the variation by anapplication state is totally evaluated. Therefore, when this phosphormixture is irradiated with any of the excitation light with thewavelength range from 300 nm to 500 nm and the emission characteristicsare measured, the value of luminance (Y) is obtained based on acalculation method in a XYZ color system defined by JISZ8701. Inaddition, the color rendering properties can also be evaluated similarlyby using the evaluation method of JISZ8726. However, the color renderingproperties are not so much affected by the variation of the lightemitting elements, and therefore the color rendering properties may beevaluated by the emission device incorporating the phosphor mixture ofthe present invention.

The aforementioned each phosphor has a preferable half value width of 50nm or more. Therefore, in the emission of this phosphor mixture,emission spectra are overlapped one another, and a so-called broadspectrum, which is continuous without being interrupted in thewavelength range from 420 nm to 750 nm, can be obtained. In addition,each phosphor has the excitation band in the same range, and thereforean adjustment of the mixing ratio is easy.

Further preferably, the emission from the phosphor mixture of thepresent invention has three or more emission peaks in the wavelengthrange from 420 nm to 680 nm in the emission spectrum in which thecorrelated color temperature is 7000K to 2500K, and has a continuousspectrum without interrupting the emission. As a result, the luminancewhereby brightness is sensed for human being's vision as an illuminationcan be gained, and simultaneously the emission has a broad emissionspectrum in the wavelength range from 420 nm to 750 nm, thus exhibitingthe emission with excellent color rendering properties.

The phosphor mixture of the present invention without lowering theemission intensity with the increase of the temperature is preferable,and therefore the phosphors with hardly deteriorated emissioncharacteristics by heating are preferably mixed. Particularly, it ispreferable to select the phosphor showing the temperature characteristicthat when the value of the emission intensity of the maximum peak of theemission spectrum at a temperature of 25° C. when the phosphor isirradiated with a specified excitation light in the wavelength rangefrom 300 nm to 500 nm is selected to be P₂₅, and the value of theemission intensity of the maximum peak of the emission spectrum at atemperature of 200° C. when the phosphor is irradiated with thespecified excitation light is selected to be P₂₀₀/(P₂₅−P₂₀₀)/P₂₅)≦30%.For example, in addition to the phosphor of the present invention, theaforementioned BAM:Eu, (Sr,Ca,Ba,Mg)₁₀(PO₄)₈Cl₂:Eu, BAM:Eu,Mn,ZnS:Cu,Al, CaAl₂Si₄N₈:Eu, CaAlSiN₃:Eu, etc, are given as examples. Thetemperature characteristics of these phosphors are shown in table 1-1.Note that this can not be limited as far as the aforementionedconditions are satisfied.

TABLE 1-1 25° C. (REFERENCE PHOSPHOR VALUE) 50° C. 100° C. 150° C. 200°C. BAM:Eu 1.00 1.01 1.01 1.04 1.08 (Sr,Ca,Ba,Mg)₁₀(PC₄)₆Cl₂:Eu 1.00 0.960.89 0.83 0.76 ZnS:Cu,Al 1.00 0.98 0.94 0.88 0.76 CaAl₂Si₄N₈:Eu 1.000.96 0.91 0.86 0.80 CaAlSiN₃:Eu 1.00 0.98 0.98 0.93 0.87

When the phosphor mixture of the present invention is used in a powderystate, the average particle size of each mixing phosphor powder ispreferably set at 50 μm or less and further preferably set at 20 μm.This is because the emission in the phosphor powder is considered tooccur mainly on the surface of a powder particle, and therefore when theaverage particle size (D50) is 50 μm or less, the surface area perpowder unit weight can be secured, and the deterioration of luminancecan be prevented. Further, in manufacturing the illumination deviceusing this phosphor mixture, when the powder is formed into a paste,which is then applied on a light emitter element, density of the powdercan be increased and fluctuation of color and deterioration of luminancecan be prevented.

Meanwhile, it is preferable to form a phosphor sheet, with the phosphormixture of the present invention dispersed in the resin.

As a material becoming a medium used in manufacturing this phosphorsheet, various kinds of resin such as epoxy resin and silicone resin orglass can be exemplified. As a use example of this phosphor sheet, aspecified emission can be performed by combining this phosphor sheet anda light source whereby a suitable emission occurs. Note that as theexcitation light for exciting this phosphor sheet, the light with thewavelength range from 250 nm to 500 nm may be selected, the light sourcemay be selected to be an ultraviolet ray light source using Hg dischargeand a light source by laser, in addition to the light emitting elementssuch as an LED.

By combining the phosphor mixture of the present invention in a powderystate with the emission part for emitting light with the wavelengthrange from 250 nm to 500 nm and preferably wavelength range from 300 nmto 500 nm, each kind of illumination device and mainly a backlight for adisplay device can be manufactured.

As the emission part, for example, an LED light emitting element foremitting light in a range from ultraviolet to blue color and a dischargelamp for generating an ultraviolet light can be used. Then, when thephosphor mixture of the present invention is combined with this LEDlight emitting element, each kind of illumination unit and the backlightfor a display device can be manufactured, and when the phosphor mixtureof the present invention is combined with this discharge lamp, each kindof fluorescent lamp, an illumination unit, and a backlight for a displaydevice, etc, can be manufactured.

A method of combining the phosphor mixture of the present invention andthe emission part may be performed by a publicly-known method. However,in a case of the emission device using the LED in the emission part, theemission device can be manufactured as follows. The emission deviceusing the LED in the emission part will be explained hereunder, withreference to the drawings.

FIGS. 26(A) to (C) are schematic sectional views of a bullet type LEDemission device, and FIGS. 27(A) to (E) are schematic sectional views ofa reflective type LED emission device. Note that in each figure, thesame signs and numerals are assigned to the corresponding parts, andexplanation therefore is omitted in some cases.

First, by using FIG. 26(A), explanation is given to an example of theemission device combined with the phosphor mixture by using the LED inthe emission part. In the bullet-type LED emission device, an LED lightemitting element 2 is set in a cup-shaped container 5 provided on thetip end of a lead frame 3, and they are molded by a translucent resin 4.In this embodiment, the phosphor mixture or a mixture with the phosphormixture dispersed in a translucent resin such as silicone and epoxy(described as mixture 1 hereunder) is embedded entirely in thecup-shaped container 5. Also, the mixture 1 may be used in an entirebody of a lens or may cover an upper part of the lens.

Next, by using FIG. 26(B), an example of a different emission devicewill be explained. In this embodiment, the mixture 1 is applied on thecup-shaped container 5 and the upper surface of the LED light emittingelement 2.

Next, by using FIG. 26(C), an example of further different emissiondevice will be explained. In this embodiment, the phosphor mixture 1 isset on the upper part of the LED light emitting element 2.

As described above, in the bullet-type LED light emission deviceexplained by using FIGS. 26(A) to (C), a direction of light emissionfrom the LED light emitting element 2 is upward. However, even if thedirection of light emission is downward, the emission device can beprepared in the same way. For example, the reflective type LED emissiondevice is constituted in such a manner that a reflective face and areflective plate are provided in the direction of light emission of theLED light emitting element 2, and the light emitted from this lightemitting element 2 is reflected by the reflective face so as to beemitted outside. Therefore, by using FIGS. 27(A) to (E), the emissiondevice in which the reflective type LED emission device and the phosphormixture of this embodiment are combined, will be explained as anexample.

First, by using FIG. 27(A), explanation is given to an example of theemission device in which the reflective type LED emission device is usedin the emission part and the reflective type LED emission device iscombined with the phosphor mixture of this embodiment. In the reflectivetype LED emission device, the LED light emitting element 2 is set on onetip end of the lead frame 3, and the light emission from this LED lightemitting element 2 occurs so as to be directed downward and reflected bythe reflective face 8 and is emitted from upward. In this embodiment,the mixture 1 is applied onto the reflective face 8. Note that atransparent mold material 9 is sometimes filled in a recessed portionformed by the reflective face 8 so as to protect the LED light emittingelement 2.

Next, by using FIG. 27(B), an example of a different emission devicewill be explained. In this embodiment, the mixture 1 is set in a lowerpart of the LED light emitting element 2.

Next, by using FIG. 27(C), an example of a different emission devicewill be explained. In this embodiment, the mixture 1 is filled in therecessed portion formed by the reflective face 8.

Next, by using FIG. 27(D), an example of a different emission devicewill be explained. In this embodiment, the mixture 1 is applied onto thetransparent mold material 9 for protecting the LED light emittingelement 2.

Next, by using FIG. 27(E), an example of a different emission devicewill be explained. In this embodiment, the mixture 1 is applied on thesurface of the LED light emitting element 2.

The bullet-type LED emission device and the reflective type LED emissiondevice may be appropriately used in accordance with application.However, the reflective type LED emission device has a merit that it canbe made thin, a light emission area can be made large, and useefficiency of light can be enhanced, and so forth.

When the emission device as described above is used as a high colorrendering illuminating light source, it is necessary to have theemission spectrum excellent in color rendering properties. Therefore, byusing the evaluation method of JISZ8726, the color rendering propertiesof the emission device incorporating the phosphor mixture including thephosphor of the present invention were evaluated. In the evaluation ofJISZ8726, when the general color rendering index Ra of this light sourceis 80 or more, this is an excellent emission device. Then, preferablywhen a special color rendering index R15, being an index showing a skincolor component of Japanese women is 80 or more and further preferablywhen a special color rendering index R9, being an index showing a redcolor component is 60 or more, this is an extremely excellent emissiondevice. However, the aforementioned index may not be satisfied,depending on the purpose of use not requiring color rendering propertiesand a different object.

Therefore, the emission device was manufactured, wherein the phosphormixture including the phosphor of the present invention was irradiatedwith the light from the emission part for emitting light in thewavelength range from 300 nm to 500 nm, so as to emit light by thisphosphor mixture. Note that as the emission part, the blue LED foremitting light having the wavelength of 460 nm and the ultraviolet LEDfor emitting light having the wavelength of 405 nm were used. Then, thecolor rendering properties of the emission spectrum of this emissiondevice was evaluated. As a result, the color rendering properties of theemission device incorporating the phosphor mixture including thephosphor of the present invention shows high color rendering propertiesof 80 or more of Ra, 80 or more of R15, and further 60 or more of R9 ina correlated color temperature range from 10000K to 2000K, andpreferably in a range from 7000K to 2500K, and it is found that thisemission device is the light source with high luminance and havingextremely excellent color rendering properties.

EXAMPLE Example 1

Commercially available SrCO₃ (3N), AlN (3N), Si₃N₄(3N), and CeO₂(3N)were prepared, and among the raw materials, 0.970 mol of SrCO₃, 1.0 molof AlN, 4.5/3 mol of Si₃N₄, and 0.030 mol of CeO₂ were weighed and mixedby using a mortar in an atmospheric air so that the molar ratio of eachelement is set at Sr:Al:Si:Ce=0.970:1:4.5:0.030. The raw material thusmixed was put in a BN crucible, then, under a nitrogen atmosphere (flowstate), temperature is increased to 1800° C. with an in-furnace pressureof 0.05 MPa set at 15° C./min, retained and fired at 1800° C. for threehours, and then cooled from 1800° C. to 200° C. for one hour.Thereafter, the firing sample thus fired was crushed to a properparticle size by using the mortar in the atmospheric air, and thephosphor of the example 1 of the composition formula expressed bySr₂Al₂Si₉O₂N₁₄:Ce (where Ce/(Sr+Ce)=0.030) was obtained. A result of acomposition analysis of the powdery phosphor thus obtained is shown intable 1-2, and an SEM photograph of the powdery phosphor (magnificationof 250 times) is shown in FIG. 1.

The result of the composition analysis of the phosphor thus obtained wasclose to a theoretical value obtained from atomic weight and a molarratio of constituent elements. A slight deviation is considered to becaused by a measurement error or impurities mixed in duringmanufacturing the phosphor. Specific surface area was 0.285 m²/g. Also,as clarified from FIG. 1, the powdery phosphor thus obtained wasaggregates in which primary particles of 20 μm or less agglutinates.When the average particle size (D50) was measured by a Laser Dopplermeasuring method, it was found that the D50 was 17.5 μm, and the size ofthe primary particle observed by an SEM diameter was 13.0 μm, which wasin a range from 1.0 μm to 20.0 μm, and the specific surface area was ina range from 0.05 m²/g to 5.0 m²/g, preferable as the phosphor.

Next, the emission spectrum of the phosphor of the example 1 wasmeasured. This measurement result is shown in table 2, and furtherdescribed in FIG. 2 and FIG. 3.

FIG. 2 and FIG. 3 are graphs where the emission intensity of thephosphor of the example 1 is taken on the ordinate axis as an relativeintensity, and the wavelength of light is taken on the abscissa axis.Here, the emission spectrum is a spectrum of the light released from thephosphor when the phosphor is irradiated with the light of a certainwavelength or energy. FIG. 2 and FIG. 3 show the spectrum of the lightemitted from the phosphor is shown by using a solid line, when thephosphor is irradiated with the monochromatic light having thewavelength of 460 nm as the excitation light, and when the phosphor isirradiated with the monochromatic light having the wavelength of 405 nmas the excitation light in the same way, respectively. Note that theemission spectrum and the excitation spectrum were measured by using aspectrofluorometer FP-6500 by Japanese JASCO International Co., Ltd.

First, by using FIG. 2, the emission spectrum of this phosphor will beexplained.

As obvious from the solid line of FIG. 2, the phosphor had the emissionspectrum with a broad peak over the broad wavelength region from 470 nmto 750 nm, and the peak wavelength thereof was 559.3 nm. (the relativeintensity of the emission intensity and the luminance at this time wereset at 100%). In addition, the half value width obtained was 117.2 nm,and the chromaticity (x, y) of the emission spectrum obtained wasx=0.4156, and y=0.5434. The powder had a yellow fluorescent color, and ayellow emission color could be visually confirmed. The phosphor of theexample 1 had a peak with extremely broad half value width over thebroad wavelength region, and therefore when used as the phosphor for theone chip type white LED illumination, the white LED illumination havingexcellent color rendering properties can be manufactured, compared withthe white LED illumination using the phosphor having a sharp peak. Inthe case of the phosphor having the sharp peak, in order to realize thespectrum close to solar light several kinds of phosphors are required tobe mixed. However, such a phosphor has a broad peak, and therefore thenumber of the kinds of the phosphors to be mixed can be decreased, andthe white LED illumination can be manufactured at a low cost.

Table 2 and the solid line of FIG. 3 show a measurement result of theemission spectrum when the phosphor is irradiated with the monochromaticlight having the wavelength of 405 nm as an excitation light. In thiscase, the phosphor had a broad peak in the broad wavelength range from470 nm to 750 nm in the excitation wavelength of 405 nm also, and thepeak wavelength was 552.3 nm. (in regards to the emission intensity andthe luminance, a peak value of the emission spectrum is defined as therelative intensity 100%, when the phosphor of the example is irradiatedwith the monochromatic light having the wavelength of 460 nm as theexcitation light.) In addition, the half value width obtained was 119.5nm. The chromaticity (x, y) of the emission spectrum was expressed byx=0.3730 and y=0.5377. Note that the yellow emission color could bevisually confirmed.

Next, an excitation spectrum of the phosphor of the example 1 will beexplained, by using FIG. 4. FIG. 4 is a graph in which the emissionintensity of the phosphor is taken on the ordinate axis, and thewavelength of the excitation light is taken on the abscissa axis. Here,the excitation spectrum is obtained by exciting the phosphor to bemeasured by using a monochromatic light with various wavelengths as anexcitation light, measuring the emission intensity of the light with afixed wavelength emitted by the phosphor, and measuring the dependencyof the emission intensity on the excitation wavelength was measured. Inthis measurement, the phosphor of the example 1 was irradiated with themonochromatic light with the wavelength from 300 nm to 570 nm, and thedependency of the emission intensity of the light having the wavelengthof 559.3 nm emitted by the phosphor, on the excitation wavelength wasmeasured.

The solid line of FIG. 4 shows the excitation spectrum of the phosphorof the example 1. As obvious from the solid line of FIG. 4, it was foundthat the excitation spectrum of the phosphor of present invention showedthe light emission of yellow color with high intensity, by theexcitation light of a broad wavelength range from 300 nm or around to500 nm. Particularly, the phosphor has a particularly excellentexcitation band in the vicinity of 460 nm and 405 nm, which are emissionwavelengths of the blue LED and the near ultraviolet/ultraviolet LEDused as the excitation light for the one chip type white LEDillumination at present.

Similarly, in regards to the emission intensity and the luminance ofexample 2, example 3, comparative example 1, comparative example 2, andcomparative example 3 as will be explained hereafter, the peak value ofthe emission spectrum is defined as the relative intensity 100%, whenthe phosphor of the example 1 is irradiated with the monochromatic lighthaving the wavelength of 460 nm as the excitation light.

Example 2

In the example 2, the phosphor of the example 2 is manufactured in thesame way as the example 1, other than the molar ratio of each element ofthe example 1 is set at Sr:Al:Si:Ce=0.970:1:5:0.030.

The commercially available SrCO₃ (3N), AlN(3N), Si₃N₄ (3N), CeO₂ (3N)were prepared, and each raw material was measured in 0.970 mol of SrCO₃,1.0 mol of AlN, 5.0/3 mol of Si₃N₄, and 0.030 mol of CeO₂, so that themolar ratio of each element was set at Sr:Al:Si:Ce=0.970:1:5:0.030, andthe raw materials thus measured was mixed in an atmospheric air by usingthe mortar. The raw materials thus mixed was put in a BN crucible, andthe temperature was increased to 1800° C. at 15° C./min, with in-furnacepressure of 0.05 MPa, in a nitrogen atmosphere (flow state), and in thiscondition, the raw materials were retained and fired for 3 hours at1800° C., then cooled from 1800° C. to 200° C. for 1 hour. Thereafter, afired sample was pulverized in an atmospheric air to obtain a suitableparticle size by using the mortar, and thus the phosphor of the example2 expressed by the composition formula Sr₃Al₃Si₁₅O₃N₂₃:Ce (whereCe/(Sr+Ce)=0.030) was obtained. Analysis results of the powdery phosphorthus obtained are shown in table 1-2.

The analysis result of the composition of the phosphor thus obtained wasclose to the theoretical value obtained from the atomic weight and themolar ratio of the constituent elements in the same way as theexample 1. The slight deviation is considered to be caused by themeasurement error or the impurities mixed in during manufacturing thephosphor. The specific surface area was 0.302 m²/g, and the primaryparticle size observed by the SEM diameter was about 12.3 μM, and theaverage particle size (D50) obtained by the laser Doppler measuringmethod was 16.85 μM, satisfying the range of not less than 1.0 μm andnot more than 20.0 μm and the range of the surface area of not more than0.05 m²/g and not less than 5.0 m²/g, which are preferable as thephosphor.

Next, the emission spectrum of the phosphor of the example 2 wasmeasured. The measurement result was shown in table 2, and furtherdescribed in FIG. 2 and FIG. 3.

One dot chain line of FIG. 2 shows the measurement result of theemission spectrum, when the phosphor is irradiated with themonochromatic light having the wavelength of 460 nm as the excitationlight. The phosphor has the spectrum with a broad peak in the broadwavelength region from 470 nm to 750 nm, and the peak wavelength was559.2 nm. In addition, the half value width obtained was 116.4 nm, andthe chromaticity (x, y) of the emission spectrum obtained was x=0.4171and y=0.5427, and a yellow emission color could be visually confirmed.

The measurement result of the emission spectrum when the phosphor wasirradiated with the monochromatic light having the wavelength of 405 nmas the excitation light was shown in table 2 and by using the one dotchain line in FIG. 3. The phosphor of the example 2 has a broad peakover the broad wavelength region from 470 nm to 750 nm in the excitationwavelength of 405 nm also, and the peak wavelength was 552.5 nm. Also,the half value width obtained was 118.0 nm, and the chromaticity (x, y)of the emission spectrum was x=0.3783 and y=0.5389. Note that the yellowfluorescent color could be visually confirmed.

The one dot chain line of FIG. 4 shows the excitation spectrum of thephosphor of the example 2. In this measurement, the phosphor of theexample 2 was irradiated with the monochromatic light with thewavelength from 300 nm to 570 nm, and an excitation dependency of theemission intensity of the light having the wavelength of 559.2 nmemitted by the phosphor was measured. As obvious from the one dot chainline of FIG. 4, the excitation spectrum of the phosphor also, in thesame way as the example 1, exhibits the yellow emission with highintensity by the excitation light with the broad wavelength region from300 nm or around to 500 nm.

The example 2 shows the composition with a large molar ratio of Si andN, compared with that of the example 1, and shows an excellent emissioncharacteristic in the same way as that of the example 1.

Example 3

In the example 3, the phosphor of the example 3 was manufactured in thesame way as the example 1, other than replacing Ce with Eu, as theactivator, in the phosphor expressed by the composition formulaSr₂Al₂Si₉O₂N₁₄:Ce (where Ce/(Sr+Ce)=0.030) of the phosphor of theexample 1. The molar ratio of each element was expressed bySr:Al:Si:Eu=0.970:1:4.5:0.030, and each raw material was measured in0.970 mol of SrCO₃, 1.0 mol of AlN, 4.5/3 mol of Si₃N₄, and 0.030/2 molof Eu₂O₃. In the same way as the example 1, the analysis result of thepowdery phosphor thus obtained is shown in table 1-2.

TABLE 1-2 AVERAGE SPECIFIC PARTICLE SURFACE COMPOSITION Sr Al Si O N CeEu OTHERS SIZE AREA FORMULA (wt %) (wt %) (wt %) (wt %) (wt %) (wt %)(wt %) (wt %) D50(μm) (m²/g) EXAMPLE 1 Sr₂Al₂Si₉O₂N₁₄: Ce 24.8 7.07 32.22.25 30.5 1.23 1.98 17.50 0.285 EXAMPLE 2 Sr₃Al₃Si₁₅O₃N₂₃: Ce 23.7 6.1133.6 2.11 30.5 1.10 2.88 16.85 0.302 EXAMPLE 3 Sr₂Al₂Si₉O₂N₁₄: Eu 24.57.13 32.3 1.83 28.1 1.32 4.82 17.27 0.291

The analysis result of the composition of the phosphor thus obtained wasclose to the theoretical value obtained by a molecular weight and themolar ratio of the constituent elements. The specific surface area was0.291 m²/g, the primary particle size observed by the SEM diameter wasabout 13.1 μm, and the average particle size (D50) obtained by the LaserDoppler measuring method was 17.27 μm. Thus, in the case of using Eu asthe activator, almost the same result as the case of using Ce as theactivator could be obtained for the composition, the specific surfacearea, and the SEM diameter.

Next, the emission spectrum of the phosphor of the example 3 wasmeasured. The measurement result is shown in table 2, and the emissionspectra when the phosphor is irradiated with the light of the excitationwavelength Ex 460 nm and Ex 405 nm are further shown in FIG. 2 and FIG.3, respectively.

Table 2 and two dot-chain line of FIG. 2 show the measurement result ofthe emission spectrum when the phosphor is irradiated with themonochromatic light having the wavelength of 460 nm as the excitationlight. It was found from the table 2 and the two dot-line of FIG. 2,that the phosphor at the excitation wavelength Ex 460 nm had a broadpeak in the broad wavelength region from 470 nm to 750 nm, and the peakwavelength was 613.8 nm. In addition, the half value width obtained was115. 6 nm, and the chromaticity (x, y) of the emission spectrum obtainedwas x=0.5573, and y=0.4330. Further, the powder had an orange color andan orange emission color could be visually confirmed.

In addition, table 2 and two dot-chain line of FIG. 3 show themeasurement result of the emission spectrum when the phosphor isirradiated with the monochromatic light having the wavelength of 405 nmas the excitation light. It was found from the table 2 and the twodot-chain line of FIG. 3, that the phosphor had the broad peak in thebroad wavelength range from 470 nm to 750 nm, and the peak wavelengthwas 607.9 nm. In addition, the half value width obtained was 114. 2 nm,and the chromaticity (x, y) of the emission spectrum obtained wasx=0.5083, and y=0.4172. Further, an orange emission color could bevisually confirmed.

The phosphor of the example 3 has the same matrix as the phosphor of theexample 1. However, by replacing the activator Ce with Eu, the peak ofthe emission spectrum could be shifted (the peak wavelength is shiftedfrom about 560 nm of Ce to about 610 nm of Eu) to the longer wavelengthside, while substantially maintaining the emission intensity. In thesilicon nitride-based phosphor and the sialon phosphor proposedheretofore, when the activator is replaced, although the peak wavelengthis shifted, a problem involved therein is that the emission intensity isdrastically decreased. However, the matrix of the example 3 ischaracterized by showing an excellent emission intensity in eitheractivator Ce or Eu. Further, the phosphor of the example 3, with thepeak wavelength being about 610 nm, exhibits an orange emission, andtherefore offers promising prospects as the phosphor for the white LEDillumination of bulb color. Further, the orange emitting phosphorproposed heretofore, in which the oxynitride and nitride are activatedby Eu, does not exceed 100 nm in the half value width of the emissionspectrum. However, the phosphor of the example 3 has a significantlybroad emission spectrum, with half value width exceeding about 120 nm.

FIG. 5 shows an excitation spectrum of the phosphor of the example 3.Note that FIG. 5 shows the graph similar to that of FIG. 4. In thismeasurement, the phosphor of the example 3 is irradiated with themonochromatic light in the wavelength range from 300 nm to 570 nm, andthe dependency of the emission intensity of the light having thewavelength of 613.8 nm emitted by the phosphor on the wavelength of theexcitation light was measured. Then, it was found from the excitationspectrum of the phosphor, that this phosphor emitted light of an orangecolor with high intensity by an excitation with the excitation lightwith a broad wavelength range from 300 nm or around to 550 nm. Further,as a result of measuring the emission intensity when the phosphor wasirradiated with the excitation light of monochromatic color in thewavelength range from 350 nm to 500 nm, when the emission intensity inthe excitation wavelength, in which the intensity of the spectrumemitted by absorbing the excitation light having the aforementionedwavelength became largest, was set at P_(H), and the emission intensityin the excitation wavelength, in which the emission intensity becamesmallest, was set at P_(L), (P_(H)−P_(L))/P_(H)≦0.10 was satisfied.Namely, variation in the emission intensity when using the monochromaticlight in the wavelength range from 350 nm to 500 nm was 10.0% or less,thereby showing a flat excitation band.

At present, although the yellow phosphor (YAG:Ce) used as the phosphorfor the white LED illumination has the excitation band with highestefficiency near the wavelength of 460 nm, it does not have theexcitation band with good efficiency over the broad range. Therefore, bydeviation of emission wavelengths due to the deviation of emissionelements on manufacturing the blue LED, the emission wavelength of theblue LED is out of an optimal excitation range of a YAG:Ce based yellowphosphor. This causes a lost of balance in the emission intensity ofblue color and yellow color, and the color tone of the white light ischanged. Meanwhile, the phosphor of the example 3 has a flat excitationband, and therefore an approximately constant emission intensity isobtained, even when the dispersion of the emission wavelengths of theemission elements occurs. This makes it possible to stably manufacturethe white LED illumination having a same color tone, and therefore thephosphor of the example 3 has an advantage in both quality andmanufacturing cost.

Comparative Example 1

The phosphor expressed by the composition formula Sr₂Si₅N₈:Ce (whereCe/(Sr+Ce)=0.030) was manufactured and defined as a comparative example1.

The phosphor of the comparative example 1 was manufactured in thefollowing way.

The commercially available samples Sr₃N₂ (2N), Si₃N₄ (3N), CeO₂ (3N)were prepared as raw materials, and each raw material, 1.94/3 mol ofSr₃N₂, 5.0/3 mold Si₃N₄, and 0.060 mol of CeO₂ were weighed and mixed ina glove box under a nitrogen atmosphere by using the mortar, so that themolar ratio of each element was expressed, satisfyingSr:Si:Ce=1.94:5.0:0.06. As per the manufacturing method as will bedescribed hereunder, other than the firing temperature which was set at1600° C., a phosphor sample was manufactured in the same way as theexample 1.

Next, in the same way as the example 1, the emission spectrum of thephosphor of the comparative example 1 was measured. The measurementresult is shown in table 2 and FIG. 2 and FIG. 3 (long broken line). Asclearly shown from the long broken line of FIG. 2 and FIG. 3, thephosphor of the comparative example 1 showed a broad emission spectrum.Also, as shown in the long broken line of FIG. 2, when the phosphor wasexcited by the light having the wavelength of 460 nm, it showed theemission spectrum with a peak in the wavelength of 557.2 nm, therelative intensity of the emission intensity was 28.5% when the relativeintensity of the example 1 was defined as 100%, and the relativeintensity of the luminance was 32.6%. In the chromaticity of theemission spectrum (x, y), x=0.3716 and y=0.5080. In addition, as shownby the long broken line of FIG. 3, the phosphor of the comparativeexample 1 showed the emission spectrum with a peak in the wavelength of562.0 nm when excited by the light of the excitation wavelength of 405nm, the relative intensity of the emission intensity was 56.4% when therelative intensity of the example 1 was defined as 100%, and therelative intensity of the luminance was 62.1%. In the chromaticity (x,y) of the emission spectrum, x=0.3901 and y=0.4985. In addition, a greencolor emission could be visually confirmed.

Comparative Example 2

The phosphor expressed by the composition formula Sr_(1.5)Al₃Si₉N₁₆:Ce(where Ce/(Sr+Ce)=0.030) was manufactured and defined as a comparativeexample 2.

The comparative example 2 was manufactured in the following way.

The commercially available samples Sr₃N₂(2N), AlN(3N), Si₃N₄(3N), andCeO₂(3N) were prepared as raw materials, the molar ratio of each elementis expressed by Sr:Al:Si:Ce=1.455:3.0:9.0:0.045, and each raw materialwas weighed in 1.455/3 mol of Sr₃N₂, 3.0 mol of AlN, 9.0/3 mol of Si₃N₄,and 0.045 mol of CeO₂ and mixed in a glove box by using a mortar underthe nitrogen atmosphere. Other than the firing temperature which was setat 1700° C., a phosphor sample was manufactured in the same way as theexample 1.

Next, in the same way as the example 1, the emission spectrum of thephosphor of the comparative example 2 was measured. The measurementresult is shown by a short broken line in table 2, FIG. 2, and FIG. 3.As clearly shown from the short broken line of FIG. 2 and FIG. 3, thephosphor of the comparative example 2 showed a broad emission spectrum.In addition, as shown by a short broken line of FIG. 2, the emissionspectrum with a peak in the wavelength of 560.8 nm was exhibited whenthe phosphor was excited by the light having the wavelength of 460 nm,the relative intensity of the emission intensity was 16.0% when therelative intensity of the example 1 was set to 100%, and the relativeintensity of the luminance was 16.7%. The chromaticity (x, y) of theemission spectrum was x=0.3992, and y=0.5116. Further, as shown by ashort broken line in FIG. 3, the phosphor of the comparative example 2showed the emission spectrum with a peak in the wavelength of 527.5 nmwhen excited by the monochromatic light of 405 nm, and when the relativeintensity of the example 1 was set to 100%, the relative intensity ofthe emission intensity was 20.9%, and the relative intensity of theluminance was 22.2%. The chromaticity (x, y) of the emission spectrumwas x=0.3316 and y=0.4958. In addition, the emission of yellow color wasvisually confirmed when the phosphor was excited by the light of thewavelength of 460 nm, and the emission of green color was confirmed whenthe phosphor was excited by the light of the wavelength of 405 nm.

Comparative Example 3

The phosphor expressed by the composition formula SrAl₂SiO₃N₂:Ce (WhereCe/(Sr+Ce)=0.030) described in the patent document 3 was manufacturedand defined as a comparative example 3.

The phosphor of the comparative example 3 was manufactured as follows.

The commercially available samples SrCO₃ (3N), AlN (3N), SiO₂ (3N), CeO₂(3N) were prepared as the raw materials, and each raw material wasweighed in 0.970 mol of SrCO₃, 2.0 mol of AlN, 1.0 mol of SiO₂, and0.030 mol of CeO₂, so that the molar ratio of each element wasSr:Al:Si:Ce=0.970:2.0:1.0:0.030, and mixed in the atmospheric air byusing the mortar. As for the manufacturing method, the phosphor wasmanufactured in the same way as the example 1, except that the firingtemperature was set at 1400° C.

Next, in the same way as the example 1, the emission spectrum of thephosphor of the comparative example 3 was measured, and it was foundthat the phosphor did not emit light when excited by the lights havingthe wavelength of 460 nm and 405 nm, thus making it impossible tomeasure. However, when the phosphor was irradiated with the excitationlight having the wavelength of 254 nm and 366 nm, the light emission ofblue color could be visually confirmed.

Further, when fired at the firing temperature of 1800° C., the rawmaterial was melted.

Study on the Examples 1, 2, 3, and the Comparative Examples 1, 2, 3

As clearly shown in the composition formula of table 2, the phosphors ofthe example 1, example 2, and example 3 having new compositions aredifferent from the comparative example and include Al in the constituentelement, have the composition formula different from that of the sialonphosphor of the comparative example 2 (sialon composition formula M_(x)(Al, Si)₁₂ (O, N)₁₆, 0<x≦1.5), and are different from the comparativeexample 3 and take a larger molar ratio of nitrogen than that of oxygen.

As clearly shown from the result of table 2, FIG. 2 and FIG. 3, comparedwith the phosphors of the comparative examples 1 to 3, the phosphors ofthe example 1, example 2, and example 3 show not less than 3 timesemission intensity and not less than 2.5 times luminance, when excitedby the light having the wavelength of 460 nm, and when excited by thelight having the wavelength of 405 nm, show not less than 1.5 timesemission intensity and luminance. Thus, it was found that theaforementioned phosphors were high-efficiency phosphors showing higheremission intensity and luminance compared with the conventionalphosphors.

TABLE 2 EXCITATION EMISSION PEAK COMPOSITION WAVELENGTH INTENSITYLUMINANCE WAVELENGTH CHROMATICITY FORMULA (nm) (%) (%) (nm) x ySr₂Al₂Si₉O₂N₁₄: Ce 460 100.0 100.0 559.3 0.416 0.543 Sr₃Al₃Si₁₅O₃N₂₃: Ce460 96.3 95.7 559.2 0.417 0.543 Sr₂Al₂Si₉O₂N₁₄: Eu 460 96.9 77.2 613.80.557 0.433 Sr₂Si₅N₈: Ce 460 28.5 32.6 557.2 0.372 0.508Sr_(1.5)Al₃Si₉N₁₆: Ce 460 16.0 16.7 560.8 0.399 0.512 SrAl₂SiO₃N₂: Ce460 UNMEASURABLE SAME AS ABOVE 405 108.1 111.8 552.3 0.373 0.538 405103.7 106.5 552.5 0.378 0.539 405 98.9 88.6 607.9 0.508 0.417 405 56.462.1 562.0 0.390 0.499 405 20.9 22.2 527.5 0.332 0.496 405 UNMEASURABLE

Example 4 to Example 13 Study on Amount of Activator Ce

In the example 4 to the example 13, change in the emission intensity andluminance of the phosphors expressed by the composition formulaSr₂Al₂Si₉O₂N₁₄:Ce were measured when the concentration of the element Z(Ce), which is an activator, was changed. Here, in manufacturing ameasurement sample, the mixing ratio of the raw materials was adjusted,so that the relation between Ce and Sr, which are activators, is m+z=1.Then, as explained in the example 1, the mixing ratio of each rawmaterial of SrCO₃ (3N), AlN (3N), Si₃N₄ (3N), CeO₂ (3N) was adjusted,and a phosphor sample was manufactured in the same way as the example 1,excepting that concentration of activator Ce was changed, and theemission intensity and luminance thus manufactured were measured.Wherein the Ce-activated concentration: Ce/(Sr+Ce) was selected to be0.001 (example 4), 0.005 (example 5), 0.010 (example 6), 0.020 (example7), 0.025 (example 8), 0.030 (example 9), 0.035 (example 10), 0.040(example 11), 0.050 (example 12), and 0.100 (example 13).

The results thus measured are shown in table 3 and FIG. 6. FIG. 6 is agraph in which the relative intensity of the emission intensity of eachof the phosphor samples is taken on the ordinate axis, and the value ofthe mixing ratio: Ce/(Sr+Ce) of Sr and Ce is taken on the abscissa axis.As for the emission intensity and luminance, the value of the emissionintensity in the peak wavelength of Ce/(Sr+Ce)=0.040 (example 11) wasset at 100%. The light having the wavelength of 460 nm was used as theexcitation light.

As clearly shown in the result of table 3 and FIG. 6, in the regionwhere the value of Ce/(Sr+Ce) is small, the emission intensity andluminance are increased in association with the increase in the value ofCe/(Sr+Ce). However, the emission intensity and luminance are decreasedin association with the increase in the value of Ce/(Sr+Ce), with thevicinity of Ce/(Sr+Ce)=0.040 as a peak. This is because an activatorelement is insufficient in a part where the value is smaller thanCe/(Sr+Ce)=0.040, and concentration quenching due to the activatorelement is observed in a part where the value is larger thanCe/(Sr+Ce)=0.040.

Meanwhile, as clearly shown in the result of table 3, in associationwith the increase in the value of Ce/(Sr+Ce), it was confirmed that thevalue of the peak wavelength was shifted to the longer wavelength side,except for the data of Ce/(Sr+Ce)=0.001 (example 4).

Along with the measurement of the emission intensity and luminance, thechromaticity (x, y) of the emission spectrum was measured, and theresult is shown in table 3.

TABLE 3 EMISSION PEAK COMPOSITION INTENSITY LUMINANCE WAVELENGTHCHROMATICITY FORMULA Z/(m + Z) (%) (%) (nm) x y EXAMPLE 4Sr₂Al₂Si₉O₂N₁₄: Ce 0.001 24.5 25.7 564.9 0.417 0.530 EXAMPLE 5 0.00560.1 61.8 557.7 0.406 0.545 EXAMPLE 6 0.010 77.4 79.0 559.2 0.408 0.546EXAMPLE 7 0.020 93.2 94.3 559.2 0.413 0.546 EXAMPLE 8 0.025 93.7 94.9559.7 0.414 0.546 EXAMPLE 9 0.030 97.2 98.2 559.7 0.416 0.545 EXAMPLE 100.035 99.4 100.4 561.4 0.416 0.542 EXAMPLE 11 0.040 100.0 100.0 561.20.423 0.543 EXAMPLE 12 0.050 95.6 95.6 561.6 0.427 0.540 EXAMPLE 130.100 38.1 38.9 564.8 0.441 0.528

Example 14 to Example 23 Study on the Amount of Activator Eu

In the examples 14 to example 23, the emission intensity and luminancewhen the concentration of the activator element Z (Eu) was changed wasmeasured, in the phosphor expressed by the composition formulaSr₂Al₂Si₉O₂N₁₄:Eu. Here, in the manufacture of the measurement sample,in the same way as the examples 4 to 13, the mixing ratio of the rawmaterials was adjusted, so that the relation between Eu and Sr, whichare activators, was m+z=1. Then, each raw material of SrCO₃ (3N),AlN(3N), Si₃N₄(3N), Eu₂O₃(3N) explained in the example 3 was adjusted,and in the same way as the example 3, the phosphor sample weremanufactured excepting that the Eu activator concentration was changed,and the emission intensity and luminance of the phosphor thusmanufactured were measured. Wherein, the Eu activator concentrationEu/(Sr+Eu) was set at 0.001 (example 14), 0.005 (example 15), 0.010(example 16), 0.020 (example 17), 0.025 (example 18), 0.030 (example19), 0.035 (example 20), 0.040 (example 21), 0.050 (example 22), 0.100(example 23).

The measurement result is shown in table 4 and FIG. 7. Here, FIG. 7 is agraph showing the relative intensity of the emission intensity of eachphosphor sample taken on the ordinate axis, and the value of theblending ratio Eu/(Sr+Eu) of Sr and Eu taken on the abscissa axis.Wherein, as for the emission intensity and luminance, the value of theemission intensity in the peak wavelength of Eu/(Sr+Eu)=0.050 (example22) was defined as 100%. The light having the wavelength of 460 nm wasused as the excitation light.

As clearly shown in table 4 and FIG. 7, in the region where the value ofEu/(Sr+Eu) is small, the emission intensity and luminance are increasedalong with the increase of the value of Eu/(Sr+Eu). However, theemission intensity and luminance are decreased, along with the increaseof the value of Eu/(Sr+Eu), with a peak in the vicinity ofEu/(Sr+Eu)=0.050. This is because the activator element is insufficientin apart where the value of the Eu/(Sr+Eu) is smaller thanEu/(Sr+Eu)=0.050, thereby causing the concentration quenching due to theactivator element to occur in a part where the value of the Eu/(Sr+Eu)is larger than Eu/(Sr+Eu)=0.050. However, gradual decrease of theemission intensity due to the concentration quenching is observed in aregion where the activator concentration is high, compared with the caseof the Ce activator concentration of the examples 4 to 13. It appearsthat this is caused by a difference of the ionic radius and thedifference of the valency between Eu and Ce.

Meanwhile, as clearly shown from the result of the table 4, it wasconfirmed that the value of the peak wavelength was shifted toward thelonger wavelength side along with the increase of the value ofEu/(Sr+Eu), except for the data of Eu/(Sr+Eu)=0.001 (example 14) andEu/(Sr+Eu)=0.050 (example 22).

In addition, in parallel to the measurement of the emission intensityand luminance, the chromaticity (x, y) of the emission spectra weremeasured. The results are shown in table 4.

TABLE 4 EMISSION PEAK COMPOSITION INTENSITY LUMINANCE WAVELENGTHCHROMATICITY FORMULA Z/(m + Z) (%) (%) (nm) x y EXAMPLE 14Sr₂Al₂Si₉O₂N₁₄: Eu 0.001 31.0 44.3 588.3 0.485 0.475 EXAMPLE 15 0.00570.2 85.1 604.6 0.526 0.456 EXAMPLE 16 0.010 79.8 93.6 605.2 0.534 0.451EXAMPLE 17 0.020 93.2 99.0 611.3 0.551 0.438 EXAMPLE 18 0.025 95.5 100.4611.1 0.554 0.437 EXAMPLE 19 0.030 97.2 96.7 615.2 0.561 0.430 EXAMPLE20 0.035 99.6 96.6 615.2 0.566 0.426 EXAMPLE 21 0.040 99.7 94.2 615.30.569 0.423 EXAMPLE 22 0.050 100.0 100.0 610.7 0.562 0.430 EXAMPLE 230.100 94.7 69.9 626.5 0.599 0.395

Example 24 to Example 32 Change of Al/Sr Ratio

In the example 24 to example 32, in regards to the phosphor expressed bythe composition formula Sr₂Al_(a)Si₉O_(o)N_(n):Ce(Ce/(Sr+Ce)=0.030,n=2/3m+a+4/3b−2/3o, m=2.0, b=9.0, O≦2.0), the molar ratio of Sr, Si isfixed to 2, 9, respectively, and the change of the emission intensityand luminance was measured when the a/m ratio (here, a/m and Al/Sr havethe same meaning) was changed. Here, in the manufacture of themeasurement samples, the phosphor samples were manufactured in the sameway as the example 1, excepting that the mixing ratio of only AlN (3N)out of each raw material of SrCO₃(3N), AlN(3N), Si₃N₄(3N), CeO₂(3N)explained in the example 1 was adjusted, and the emission intensity andluminance of the phosphor thus manufactured were measured. Wherein, theblending ratio of Al and Sr thus adjusted was set at Al/Sr=0.50 (example24), Al/Sr=0.75 (example 25), Al/Sr=0.90 (example 26), Al/Sr=1.00(example 27), Al/Sr=1.10 (example 28), Al/Sr=1.25 (example 29),Al/Sr=1.50 (example 30), Al/Sr=2.00 (example 31), and Al/Sr=3.00(example 32).

The measurement results are shown in table 5 and FIG. 8. Here, FIG. 8 isa graph showing the relative intensity of the emission intensity of eachphosphor sample taken on the ordinate axis, and the value of theblending ratio: Al/Sr of Sr and Al taken on the abscissa axis. Inregards to the emission intensity and luminance, the value of theemission intensity in the peak wavelength of Al/Sr=1.0 (example 27) wasdefined as 100%. The value of Al/Sr was adjusted at 0.50 to 3.00, andthe results are shown. The light having the wavelength of 460 nm wasused as the excitation light.

As being clarified from the results of table 5 and FIG. 8, the emissionintensity and luminance are increased along with the increase of thevalue of Al/Sr in the region where the value is small. However theemission intensity and luminance are decreased, with a peak in thevicinity of Al/Sr=1.0 (example 27).

This is because when the value of Al/Sr is largely deviated fromAl/Sr=1.0, an unreacted raw material is remained in the phosphor afterfiring, the phase different from a light emitting phase is generated,and the crystallinity of the matrix structure of the phosphor isdeteriorated because the X-ray diffraction peak intensity is reducedwhen Al/Sr is not less than 1.5, and further the structure suitable forlight emission is collapsed, to generate the impurity phase notcontributing to the light emission. Thus, when the value of Al/Sr isdeviated from Al/Sr=1.0, the emission intensity and luminance aredeteriorated. However, a suitable Al content changes a little dependingupon deviation of Si and O composition, if such a deviation is small,the influence is also small, and when the Al/Sr is in the range of0.75≦Al/Sr<1.5, 80% or more value of the emission intensity andluminance of Al/Sr=1.0 is exhibited.

TABLE 5 EMISSION PEAK COMPOSITION INTENSITY LUMINANCE WAVELENGTHCHROMATICITY FORMULA Al/Sr (%) (%) (nm) x y EXAMPLE 24Sr₂Al_(1.0)Si₉O₂N_(13.0): Ce 0.50 43.8 44.4 562.4 0.421 0.529 EXAMPLE 25Sr₂Al_(1.5)Si₉O₂N_(13.5): Ce 0.75 82.9 83.3 562.1 0.421 0.537 EXAMPLE 26Sr₂Al_(1.8)Si₉O₂N_(13.8): Ce 0.90 95.4 95.4 561.6 0.418 0.541 EXAMPLE 27Sr₂Al_(2.0)Si₉O₂N_(14.0): Ce 1.00 100.0 100.0 559.3 0.416 0.543 EXAMPLE28 Sr₂Al_(2.2)Si₉O₂N_(14.2): Ce 1.10 94.8 102.4 559.2 0.413 0.545EXAMPLE 29 Sr₂Al_(2.5)Si₉O₂N_(14.5): Ce 1.25 87.2 94.6 559.2 0.411 0.545EXAMPLE 30 Sr₂Al_(3.0)Si₉O₂N_(15.0): Ce 1.50 70.9 76.9 559.7 0.411 0.542EXAMPLE 31 Sr₂Al_(4.0)Si₉O₂N_(16.0): Ce 2.00 61.0 66.3 559.7 0.411 0.540EXAMPLE 32 Sr₂Al_(6.0)Si₉O₂N_(18.0): Ce 3.00 53.1 53.3 557.5 0.404 0.538

Examples 33 to 42 Change of Si/Sr

In the examples 33 to 42, the molar ratio of Sr, Al, is fixed to 2, 2,respectively in the phosphor expressed by the composition formulaSr₂Al₂Si_(b)O₂N_(n):Ce_(0.060)(Ce/(Sr+Ce)=0.030, n=2/3m+a+4/3b−2/3o,wherein m=2.0, a=2.0), and the change of the emission intensity andluminance were measured when the b/m ratio (here, b/m and Si/Sr have thesame meaning.) was changed. Here, in the manufacture of the measurementsamples, the phosphor sample was manufactured in the same way as theexample 1, excepting that the mixing ratio of only Si₃N₄(3N) out of eachraw material of SrCO₃(3N), AlN(3N), Si₃N₄(3N), CeO₂(3N) explained in theexample 1 was adjusted, and the emission intensity and luminance of thephosphors thus manufactured were measured. Wherein the blending ratio ofSi and Sr was set at Si/Sr=1.0 (example 33), Si/Sr=1.5 (example 34),Si/Sr=2.0 (example 35), Si/Sr=3.0 (example 36), Si/Sr=4.0 (example 37),Si/Sr=4.5 (example 38), Si/Sr=5.0 (example 39), Si/Sr=5.5 (example 40),Si/Sr=6.0 (example 41), Si/Sr=7.0 (example 42).

The measurement results will be explained with reference to table 6 andFIG. 9. Here, FIG. 9 shows the relative intensity of the emissionintensity of the phosphor samples taken on the ordinate axis, and thevalue of the blending ratio Si/Sr of Sr and Si taken on the abscissaaxis. In regards to the emission intensity and luminance, the value ofthe emission intensity in the peak wavelength of Si/Sr=4.5 (example 38)was defined as 100%. The value of Si/Sr is adjusted to 1.0 to 7.0, andthe results are shown. The light having the wavelength of 460 nm wasused as the excitation light.

TABLE 6 EXCITATION EMISSION PEAK COMPOSITION WAVELENGTH INTENSITYLUMINANCE WAVELENGTH CHROMATICITY FORMULA Si/Sr (nm) (%) (%) (nm) x yEXAMPLE 33 Sr₂Al₂Si₂O₂N_(4.67): Ce 1.00 460 12.2 13.2 568.1 0.413 0.495EXAMPLE 34 Sr₂Al₂Si₃O₂N_(6.00): Ce 1.50 460 34.2 36.6 566.2 0.423 0.516EXAMPLE 35 Sr₂Al₂Si₄O₂N_(7.33): Ce 2.00 460 45.8 49.4 564.8 0.416 0.524EXAMPLE 36 Sr₂Al₂Si₆O₂N_(10.00): Ce 3.00 460 69.8 74.8 560.7 0.405 0.535EXAMPLE 37 Sr₂Al₂Si₈O₂N_(12.67): Ce 4.00 460 94.7 96.2 559.0 0.409 0.543EXAMPLE 38 Sr₂Al₂Si₉O₂N_(14.00): Ce 4.50 460 100.0 100.0 559.3 0.4160.543 EXAMPLE 39 Sr₂Al₂Si₁₀O₂N_(15.33): Ce 5.00 460 96.3 95.7 559.20.417 0.543 EXAMPLE 40 Sr₂Al₂Si₁₁O₂N_(16.67): Ce 5.50 460 80.2 86.2559.7 0.419 0.541 EXAMPLE 41 Sr₂Al₂Si₁₂O₂N_(18.00): Ce 6.00 460 61.661.0 562.3 0.424 0.534 EXAMPLE 42 Sr₂Al₂Si₁₄O₂N_(20.67): Ce 7.00 460UNMEASURABLE

As being clarified from the result of FIG. 9, the emission intensity wasincreased along with the increase of the value of Si/Sr in the regionwhere the value of Si/Sr was small, with a peak at Si/Sr=4.5 (example38), and when the value of Si/Sr exceeds Si/Sr=4.5, the emissionintensity was deteriorated. This is because, in the same way asexplained for Al/Sr in the examples 24 to 32, when the value of Si/Sr islargely deviated from Si/Sr=4.5, an unreacted raw material is remainedin the phosphor after firing, the impurity phase is generated, and thecrystallinity of the matrix structure of the phosphor is deterioratedbecause the X-ray diffraction peak intensity is reduced, and further thestructure suitable for light emission is collapsed. Particularly, whenthe value of Si/Sr is selected to be smaller than 4.5, the peak observedon the lower angle side disappears, and a new peak is confirmed toappear. Meanwhile, when the value of Si/Sr is selected to be larger than4.5, the peak observed on the lower angle side is confirmed todisappear. This reveals that when the value of Si/Sr is largely deviatedfrom the relation of Si/Sr=4.5, the impurity phase not contributing tothe light emission is generated. However, if the deviation is small, theinfluence is also small, and when the value of Si/Sr is in the range of3.5≦Si/Sr≦6.0, 80% or more value of the emission intensity and luminanceof Si/Sr=4.5 is exhibited.

Example 43 to Example 50 Change of Sr Molar Ratio

In regards to the phosphor expressed by the composition formulaSr_(m)Al₂Si₉O₂N_(n):Ce (Ce/(Sr+Ce)=0.030, n=2/3m+a+4/3b−2/3o, whereina=2.0, b=9.0, o=2.0), the molar ratio of Al, Si, is fixed to 2, 9,respectively, and the change of the emission intensity and luminance wasmeasured when the molar ratio of Sr (here, m and Sr have the samemeaning, i.e. m=Sr) was changed. Here, in the manufacture of themeasurement sample, the phosphor samples were manufactured in the sameway as the example 1, excepting that the mixing ratio was adjusted byadding Al₂O₃ (3N) raw material to always obtain the value of 0 as o=2.0in addition to SrCO₃(3N), AlN(3N), Si₃N₄(3N), and CeO₂(3N) explained inthe example 1, and the emission intensity and luminance of the phosphorthus manufactured were measured. Wherein, the molar ratios of Sr thusadjusted were set at Sr=0.50 (example 43), Sr=1.00 (example 44), Sr=1.50(example 45), Sr=2.00 (example 46), Sr=2.50 (example 47), Sr=3.0(example 48), Sr=4.0 (example 49), and Sr=6.0 (example 50).

The measurement result will be explained with reference to table 7 andFIG. 10. Here, FIG. 10 is a graph showing the relative intensity of theemission intensity of the phosphor sample taken on the ordinate axis,and the value of Sr molar ratio taken on the abscissa axis. In regardsto the emission intensity and luminance, the value of the emissionintensity in the peak wavelength of Sr=2.00 (example 46) was defined as100%. The value of the Sr molar ratios is adjusted to 0.50 to 6.00, andthe results are shown. The light having the wavelength of 460 nm wasused as the excitation light.

TABLE 7 Sr EXCITATION EMISSION PEAK COMPOSITION MOLAR WAVELENGTHINTENSITY LUMINANCE WAVELENGTH CHROMATICITY FORMULA RATIO (nm) (%) (%)(nm) x y EXAMPLE 43 Sr0.50Al2Si9O2N13.00: Ce 0.50 460 MEASUREMENTIMPOSSIBILITY EXAMPLE 44 Sr1.00Al2Si9O2N13.33: Ce 1.00 460 MEASUREMENTIMPOSSIBILITY EXAMPLE 45 Sr1.50Al2Si9O2N13.67: Ce 1.50 460 64.1 63.7559.1 0.411 0.538 EXAMPLE 46 Sr2.00Al2Si9O2N14.00: Ce 2.00 460 100.0100.0 559.7 0.410 0.542 EXAMPLE 47 Sr2.50Al2Si9O2N14.33: Ce 2.50 46096.5 98.7 561.6 0.407 0.536 EXAMPLE 48 Sr3.00Al2Si9O2N14:64: Ce 3.00 46085.9 89.6 561.6 0.400 0.536 EXAMPLE 49 Sr4.00Al2Si9O2N15.33: Ce 4.00 46068.5 72.6 561.6 0.398 0.532 EXAMPLE 50 Sr6.00Al2Si9O2N16.67: Ce 6.00 46061.8 64.1 565.6 0.425 0.520

As being clarified from the result of FIG. 10, with smaller molar ratioof 0.50 (example 43) and 1.00 (example 44), the light emission was notobtained when the phosphor samples were irradiated with the light havingthe wavelength of 460 nm and 405 nm. Further, as an easy evaluation,when the phosphor samples were irradiated with the light of anultraviolet lamp having the wavelength of 366 nm, blue emission colorcould be visually confirmed. This is because with smaller molar ratio of0.50 and 1.00, the proportion of SrCO₃ as a Sr raw material in the mixedpowder is small, and the SrCO₃ does not excellently act as flux, not togenerate the phase emitting yellow light but to generate other phase,thus exhibiting blue light emission under the excitation light of shortwavelength. In addition, when the Sr molar ratio is gradually increasedfrom 1.00, the emission intensity and luminance are increased along withthe increase of the Sr molar ratio, with a peak at Sr=2.00 (example 46).However, the emission intensity is decreased when the value of Srbecomes beyond 2.00.

Example 51 to Example 60 Change of Oxygen Content

In the example 51 to example 60, in regards to the phosphor expressed bythe composition formula Sr₂Al₂Si₉O_(o)N_(n):Ce (Ce/(Sr+Ce)=0.030,n=2/3m+a+4/3b−2/3o, m=2.0, a=2.0, b=9.0), the molar ratio of Sr, Al, Siis fixed to 2, 2, 9, respectively, and the change of the emissionintensity and luminance was measured when the o/m ratio (oxygen content)was changed. Here, in the manufacture of the measurement samples, thephosphor samples were manufactured in the same way as the example 1,excepting that the oxygen content was changed by mixing each rawmaterial of Sr₃N₂ (2N), SrCO₃ (3N), AlN(3N), Al₂O₃(3N), Si₃N₄ (3N),SiO₂(3N), and CeO₂ (3N) at a predetermined molar ratio, and the emissionintensity and luminance were measured.

As for the example in which the o/m ratio adjusted at weighing rawmaterials is o/m=0.0 (example 51), o/m=0.2 (example 52), and o/m=0.50(example 53), Sr₃N₂, Al₂O₃, AlN, Si₃N₄ were used as raw materials, andas for the example in which the adjusted o/m ratio was o/m=1.00 (example54), o/m=1.25 (example 55), o/m=1.5 (example 56), o/m=2.0 (example 57),and o/m=3.0 (example 58), SrCO₃, Al₂O₃, AlN, SiO₂, and Si₃N₄ were usedas the raw materials, and as for the example in which the adjusted o/mratio was o/m=5.0 (example 59), o/m=10.0 (example 60), Sr₃N₂, Al₂O₃,SiO₂, and Si₃N₄ were used as the raw materials.

The measurement result will be explained with reference to table 8 andFIG. 11. Here, FIG. 11 is a graph showing the relative intensity of theemission intensity of the phosphor sample taken on the ordinate axis,and the value of the oxygen content (weight %) in the phosphor taken onthe abscissa axis. In the emission intensity and luminance, the value ofthe emission intensity in the peak wavelength of o/m=1.0 (example 54)was defined as 100%. The light having the wavelength of 460 nm was usedas the excitation light.

As being clarified from the result of table 8 and FIG. 11, the emissionintensity and luminance of each phosphor are decreased in both cases ofincreasing or decreasing the oxygen content with a peak between 2.5 and3.5 wt %, and are extremely decreased in case of the oxygen content of4.0 wt % or more. Further, when the oxygen content becomes 10.0 wt % ormore, each phosphor is melted and vitrified.

TABLE 8 EMISSION PEAK COMPOSITION INTENSITY LUMINANCE WAVELENGTHCHROMATICITY O N FORMULA o/m (%) (%) (nm) x y (wt %) (wt %) EXAMPLE 51Sr₂Al₂Si₉O_(0.00)N_(15.33): Ce 0.00 63.7 60.5 561.7 0.424 0.532 1.4429.1 EXAMPLE 52 Sr₂Al₂Si₉O_(0.40)N_(15.07): Ce 0.20 42.6 41.0 561.20.413 0.532 2.08 29.6 EXAMPLE 53 Sr₂Al₂Si₉O_(1.00)N_(14.67): Ce 0.5047.6 45.8 561.2 0.411 0.530 2.10 28.1 EXAMPLE 54Sr₂Al₂Si₉O_(2.00)N_(14.00): Ce 1.00 100.0 100.0 559.7 0.410 0.541 2.6827.2 EXAMPLE 55 Sr₂Al₂Si₉O_(2.50)N_(13.67): Ce 1.25 96.3 96.4 558.10.404 0.542 3.56 26.9 EXAMPLE 56 Sr₂Al₂Si₉O_(3.00)N_(13.33): Ce 1.5080.2 80.5 558.1 0.404 0.540 4.12 26.4 EXAMPLE 57Sr₂Al₂Si₉O_(4.00)N_(12.67): Ce 2.00 53.8 53.9 559.1 0.394 0.532 5.2225.1 EXAMPLE 58 Sr₂Al₂Si₉O_(6.00)N_(11.33): Ce 3.00 28.2 25.4 554.60.367 0.505 9.42 21.7 EXAMPLE 59 Sr₂Al₂Si₉O_(10.0)N_(8.67): Ce 5.00UNMEASURABLE EXAMPLE 60 Sr₂Al₂Si₉O_(20.0)N_(2.00): Ce 10.00 UNMEASURABLE

This is because when the oxygen content becomes not less than 4.0 wt %,the matrix structure of the phosphor begins to gradually vitrified, andcompletely vitrified at 10.0 wt % or more, thereby collapsing thecrystal structure and deteriorating the crystallinity. Actually, whenthe X-ray diffraction measurement was performed for the samples havingdifferent oxygen content, it was confirmed that the peak intensity ofdiffraction was significantly lowered along with the increase of theoxygen content, and the half value width of the peak was graduallyenlarged, and each phosphor was vitrified along with the increase of theoxygen content. When the matrix structure of the phosphor was vitrified,the structure around Ce ion as the center of light emission becomesirregular, to cause a variance in the interval between each center oflight emission, or efficient light emission is obtained at some placebut no light emission is obtained at another place because an energyfrom the excitation light absorbed by the matrix body can not beefficiently transferred to the center of the light emission, andtherefore the emission intensity as an entire body of the phosphor isdeteriorated. Accordingly, preferably 10 wt % or less of the oxygencontent in the phosphor is preferable. When the emission characteristicand powder characteristics after firing are taken into consideration,0.5 wt % or more and 8.1 wt % or less (in the range of 0.0<o/m≦4.0 whendefined in terms of molar ratio) is preferable. More preferably, whenthe oxygen content is in the range from 0.5 wt % to 5.0 wt % (in therange of 0.0<o/m≦3.0), it appears that sufficient emission intensity andluminance can be obtained.

Next, in examples 61 to 82, samples were manufactured by increasingamounts of Al and oxygen in the composition during mixing the rawmaterials and the emission characteristics and the temperaturecharacteristics were compared.

Example 61

In the example 61, the phosphor having a target composition after firingexpressed by

SrAl_(1.43)Si_(3.81)O_(0.59)N_(6.79):Ce (wherein Ce/(Sr+Ce)=0.030) wasmanufactured.

The commercially available SrCO₃ (3N), AlN (3N), Al₂O₃ (3N), Al₂O₃ (3N),Si₃N₄ (3N), CeO₂ (3N) were prepared as the raw materials, and each rawmaterial, SrCO₃ of 0.970 mol, Al₂O₃ of (1.31-0.976)/3 mol, AlN of1.3−((1.31-0.976)/3)×2 mol, Si₃N₄ of 4.5/3 mol, and 0.030 mol of CeO₂,were weighed so that the molar ratio of each element wasSr:Al:Si:O:Ce=0.970:1.3:4.5:1.31:0.030, and mixed in the atmospheric airby using the mortar. Note that the phosphor thus manufactured isexpressed by a mixed composition formula ofSrAl_(1.3)Si_(4.5)O_(1.31)N_(7.1):Ce. The examples 61 to 82 are notshown by the mixed composition formula but shown by the targetcomposition.

In the same way as the example 1, the raw material thus mixed was put ina BN crucible, then after vacuuming inside the furnace, temperature isincreased to 1800° C. with an in-furnace pressure of 0.05 MPa set at 15°C./min, retained and fired at 1800° C. for three hours in a nitrogenatmosphere (flow state 20.0 l/min), and then cooled from 1800° C. to 50°C. for one hour and half. Thereafter, the firing sample thus fired wascrushed to a proper particle size by using the mortar in the atmosphericair, and the phosphor of the example 61 of the composition formulaexpressed by SrAl_(1.43)Si_(3.81)O_(0.59)N_(6.79):Ce (whereCe/(Sr+Ce)=0.030) was obtained.

A result of analysis, the average particle size (D50) and the specificsurface area (BET) of the obtained phosphor powder, are shown in table9. Note that Si was measured by a weight method (an absorptionmetry),the other elements were measured by ICP, the average particle size (D50)was measured by a laser diffraction scattering method, and the specificsurface area was measured by a BET method. The obtained phosphor powdershowed the average particle size (D50) of 24.40 μm and the specificsurface area of 0.225 m²/g, and it was found that these values were in arange from 1.0 μm to 50.0 μm, which was a preferable size as thephosphor powder.

Next, the emission spectrum of the phosphor of the example 61 wasmeasured. This measurement result is shown in table 10, and is furthershown in FIG. 12. FIG. 12 is a graph showing the emission intensity ofthe phosphor taken on the ordinate axis as the relative intensity, andthe wavelength of the light taken on the abscissa axis. Here, theemission spectrum is the spectrum of the light released from thephosphor, when the phosphor is irradiated with the light of a certainwavelength or energy. The spectrum of the light emitted from thephosphor is shown by solid line of FIG. 12, when the phosphor of theexample 61 is irradiated with the monochromatic light having thewavelength of 460 nm as the excitation light.

As is obvious from FIG. 12, the phosphor had the emission spectrum witha broad peak over the broad wavelength region from 470 nm to 750 nm, andthe peak wavelength thereof was 556.0 nm. (relative intensity of theemission intensity at this time were set at 100%). In addition, the halfvalue width obtained was 117.1 nm, and the chromaticity (x, y) of theemission spectrum obtained was x=0.4045, and y=0.5481. Powder had ayellow fluorescent color, and a yellow-green emission color could bevisually confirmed. The phosphor of the example 61 had a peak withextremely broad half value width such as 100 nm or more over the broadwavelength region, and therefore when used as a white LED illuminatingphosphor, the white LED illumination having excellent luminance andcolor rendering properties can be manufactured, compared with one usingthe phosphor having a sharp peak. In the case of the phosphor having thesharp peak, several kinds of phosphors are required to be mixed toimprove the color rendering properties. However, the phosphor of theexample 61 has a broad peak, and therefore the number of the kinds ofthe phosphors to be mixed can be decreased, and the white LEDillumination can be manufactured at a low cost.

Further, when the phosphor of the example 61 is irradiated with themonochromatic light having the wavelength of 405 nm as the excitationlight, the spectrum of the light emitted from the phosphor is shown intable 10, and is further shown by broken line in FIG. 12. When thephosphor is irradiated with Ex405 nm, the emission intensity is improvedby about 20% as compared to a case of Ex460 nm. The peak wavelength was531.5 nm and the half value width was 118.1 nm, and the half value widthof the emission spectrum was 80 nm or more. The chromaticity (x, y) wasx=0.3476, and y=0.5305.

Next, by using FIG. 13, the excitation spectrum of the phosphor of theexample 61 will be explained. FIG. 13 is a graph showing the emissionintensity of the phosphor taken on the ordinate axis, and the wavelengthof the excitation light taken on the abscissa axis. Here, the excitationspectrum is obtained by measuring the emission intensity with a fixedwavelength emitted from the phosphor and measuring an excitationwavelength dependency of the emission intensity, when the phosphor to bemeasured is excited using the monochromatic light of various wavelengthsas the excitation light. In this measurement, the phosphor of theexample 61 was irradiated with the monochromatic light with thewavelength range from 250 nm to 550 nm, and the excitation dependency ofthe emission intensity of the light having the wavelength of 556.0nm(green light) emitted form the phosphor was measured.

As is obvious from FIG. 13, it was found that green color emission withhigh intensity was shown by the excitation light in a broad wavelengthrange from about 300 nm to about 500 nm. Particularly, highest emissionefficiency is shown by the excitation light in the wavelength range from400 nm to 480 nm, and at present, the emission device having highluminance can be manufactured by combining the phosphor with the blueLED with the emission wavelength of 460 nm and thenear-ultraviolet/ultraviolet LED having the wavelength of 405 nm used asthe excitation light for the one-chip type white LED illumination.

Next, the temperature characteristics of the emission intensity of thephosphor obtained by the example 61 were measured. This measurementresult is shown in table 10 and is further shown in FIG. 14.

The temperature of this phosphor was increased to 25° C., 50° C., 100°C., 150° C., 200° C., 250° C., 300° C., and after it reaches ameasurement temperature, the temperature was retained for 5 minutes sothat the temperature of an overall samples becomes uniform, andthereafter the emission intensity was measured. Also, the emissionintensity at each measurement temperature was measured as the relativeintensity, with a value of the emission intensity at a room temperature(25° C.) before increasing the temperature set at 100%. Note that aftermeasuring the emission intensity during increasing the temperature, thephosphor was cooled, and the emission intensity was measured again at25° C. Further, the same measurement was performed when the phosphor wasirradiated with the monochromatic light having the wavelength of 405 nmas the excitation light.

FIGS. 14A and 14B are graphs showing the relative emission intensitytaken on the ordinate axis, with the emission intensity beforeincreasing the temperature (25° C.) set at 100%, and showing ameasurement temperature taken on the abscissa axis at which the emissionintensity of the phosphor is measured, wherein FIG. 14A shows a casethat the phosphor is irradiated with the monochromatic light having thewavelength of 460 nm as the excitation light, and FIG. 14B shows a casethat the phosphor is irradiated with the monochromatic light having thewavelength of 405 nm as the excitation light. The measurement results ofthe phosphor of the example 61 are shown by thick solid lines in theFIGS. 14A and 14.B.

From the result of FIG. 14A, when the phosphor of the example 61 wasirradiated with the monochromatic light having the wavelength of 460 nmas the excitation light, the emission intensity showed the values of94.4% at the measurement temperature of 100° C., 85.8% at 200° C., and73.4% at 300° C., when the value of the emission intensity at the roomtemperature (25° C.) before increasing the measurement temperature wasset at 100%. After increasing the temperature, the phosphor was cooled,and the measurement at 25° C. again showed 98.8%, and almost no decreaseof emission intensity was observed, and even if it was observed, it waswithin a measurement error.

When the phosphor of the example 61 was irradiated with themonochromatic light having the wavelength of 405 nm as the excitationlight (25° C.), the emission intensity of 119.9% was shown, with thevalue of the emission intensity set at 100% when the phosphor of theexample 61 was irradiated with the monochromatic light having thewavelength of 460 nm as the excitation light. Next, from the result ofFIG. 14B, when the value of the emission intensity at the roomtemperature (25° C.) before increasing the measurement temperature wasset at 100%, the emission intensity showed the values of 92.0% at themeasurement temperature of 100° C., 80.9% at 200° C., 66.5% at 300° C.After increasing the temperature, the phosphor was cooled, and theemission intensity was measured again at 25° C., and it showed 98.9%.Almost no decrease of emission intensity was observed, and even if itwas observed, it was within a measurement error.

Example 62

In an example 62, the phosphor having a target composition after firingexpressed by SrAl_(1.33)Si_(4.09)O_(0.65)N_(7.02):Ce (whereinCe/(Sr+Ce)=0.030) was manufactured. The phosphor of the example 62expressed by the composition formulaSrAl_(1.33)Si_(4.09)O_(0.65)N_(7.02):Ce (wherein Ce/(Sr+Ce)=0.030) wasobtained in the same way as the example 61, other than that duringmixing the raw materials, each raw material was weighed in SrCO₃ of0.970 mol, Al₂O₃ of (1.31−0.976)/3 mol, AlN of 1.25−((1.31−0.976)/3)×2mol, Si₃N₄ of 4.75/3 mol, and CeO₂ of 0.030 mol, so that the molar ratioof each element is Sr:Al:Si:O:Ce=0.970:1.25:4.75:1.31:0.030. As analysisresults, the average particle size (D50) and the specific surface area(BET) of the obtained phosphor powder are shown in table 9. The specificsurface area of the obtained phosphor was 0.264 m²/g. It was found thatthe average particle size (D50) was not less than 1.0 μm and not morethan 50.0 μm which was preferable as the phosphor powder.

Next, in the same ways as the example 61, the emission spectrum of thephosphor of the example 62 was measured. The measurement result is shownin table 10. As shown in the table 10, when the phosphor was irradiatedwith the monochromatic light having the wavelength of 460 nm as theexcitation light, the emission spectrum of this phosphor had a broadpeak in a broad wavelength range from 470 nm to 750 nm in the same wayas the phosphor of the example 61, and the peak wavelength was 555.6 nm.Also, the half value width was 115.6 nm and the chromaticity (x, y) ofthe emission spectrum was x=0.4040, y=0.5481. Note that the powdershowed the fluorescent color of yellow, and a green emission color couldbe visually confirmed. When the relative intensity of the phosphor ofthe example 61 was set at 100%, the relative intensity of the emissionintensity of the phosphor of the example 62 was 94.0%.

Next, as shown in table 10, when the phosphor was irradiated with themonochromatic light having the wavelength of 405 nm as the excitationlight, the emission spectrum of this phosphor had a broad peak in abroad wavelength range from 470 nm to 750 nm in the same way as thephosphor of the example 61, and the peak wavelength was 533.5 nm. Also,the half value width was 116.2 nm and the chromaticity (x, y) of theemission spectrum was x=0.3508, y=0.5340. Note that the powder showedthe fluorescent color of yellow and a green emission could be visuallyconfirmed. When the relative intensity of the phosphor of the example 61was set at 100%, the relative intensity of the emission intensity of thephosphor of the example 62 was 110.9%.

Next, when the phosphor of the example 62 was irradiated with themonochromatic light in the wavelength range from 250 nm to 550 nm, andthe excitation dependency of the emission intensity having thewavelength of 555.6 nm emitted from this phosphor was measured, it wasfound that in the same way as the phosphor of the example 61, theexcitation spectrum of this phosphor showed green color emission withhigh intensity by the excitation light in a broad wavelength range fromabout 300 nm to 500 nm.

Next, the temperature characteristics of the emission intensity of theobtained phosphor in the example 62 were measured in the same way as theexample 61. This measurement result is shown in table 10, and further isshown in FIGS. 14A and 14B in the same way as the example 61 by using athick one dot chain line.

From the result of FIG. 14A, when the phosphor of the example 62 wasirradiated with the monochromatic light having the wavelength of 460 nmas the excitation light, the emission intensity showed 93.0% at themeasurement temperature of 100° C., 83.8% at 200° C., and 70.8% at 300°C., when the value of the emission intensity at the room temperature(25° C.) before increasing the measurement temperature was set at 100%.After increasing the temperature, the phosphor was cooled and theemission intensity was measured again at 25° C., it showed 98.4%, andalmost no decrease of emission intensity was observed, and even if itwas observed, it was within the measurement error.

From the result of FIG. 14B, when the phosphor of the example 62 wasirradiated with the monochromatic light having the wavelength of 405 nmas the excitation light, the emission intensity showed 90.9% at themeasurement temperature of 100° C., 78.8% at 200° C., and 64.6% at 300°C., when the value of the emission intensity at the room temperature(25° C.) before increasing the measurement temperature was set at 100%.After increasing the temperature, the phosphor was cooled and when theemission intensity was measured again at 25° C., it showed 98.6%, andalmost no decrease of emission intensity could be observed, and even ifit was observed, it was within the measurement error.

The phosphor of the example 62 has a slightly different molar ratio ofAl, Si, N, O from the phosphor of the example 61, but showed excellentemission characteristics in the same way as the example 61.

Example 63

In the example 63, the phosphor having a target composition after firingexpressed by SrAl_(1.28)Si_(3.40)O_(0.72)N_(5.99):Ce (whereinCe/(Sr+Ce)=0.030) was manufactured.

The phosphor of the example 63 expressed by the composition formulaSrAl_(1.28)Si_(3.40)O_(0.72)N_(5.99):Ce (wherein Ce/(Sr+Ce)=0.030) wasobtained in the same way as the example 61, other than that each rawmaterial was weighed in SrCO₃ of 0.970 mol, Al₂O₃ of (1.56−0.976)/3 mol,AlN of 1.25−((1.56−0.976)/3)×2 mol, Si₃N₄ of 4.25/3 mol, and CeO₂ of0.030 mol, so that the molar ratio of each element becomesSr:Al:Si:O:Ce=0.970:1.25:4.25:1.56:0.030. As analysis results, theaverage particle size (D50) and the specific surface area (BET) of theobtained phosphor powder are shown in table 9. It was found that thespecific surface area of the obtained phosphor was 0.231 m²/g and theaverage particle size (D50) was not less than 1.0 μm and not more than50.0 μm which were preferable as the phosphor powder.

Next, in the same way as the example 61, the emission spectrum of thephosphor of the example 63 was measured. This measurement result isshown in table 10. Table 10 shows the measurement results of theemission spectra when the phosphor is irradiated with the monochromaticlight having the wavelengths of 460 nmm and 405 nm. And when thephosphor was irradiated with the monochromatic light having thewavelength of 460 nm as the excitation light, this phosphor had a broadpeak in a broad wavelength range form 470 nm to 750 nm in the same wayas the phosphor of the example 61, and the peak wavelength was 555.6 nm.Also, the half value width was 116.0 nm, and the chromaticity (x, y) ofthe emission spectrum was x=0.3996, y=0.5498. Note that the powdershowed the fluorescent color of yellow and the green emission colorcould be visually confirmed. Then, the relative intensity of theemission intensity of the phosphor according to the example 63 was93.5%, when the relative intensity of the phosphor of the example 61 wasset at 100%.

Next, as shown in table 10, when the phosphor was irradiated with themonochromatic light having the wavelength of 405 nm as the excitationlight, the emission spectrum of this phosphor had a broad peak in abroad wavelength range form 470 nm to 750 nm in the same way as thephosphor of the example 61, and the peak wavelength was 530.4 nm. Also,the half value width was 115.9 nm and the chromaticity (x, y) of theemission spectrum was x=0.3434, y=0.5302. Note that the powder showedthe fluorescent color of yellow, and the green emission color could bevisually confirmed. When the relative intensity of the phosphor of theexample 61 was set at 100%, the relative intensity of the emissionintensity of the phosphor according to the example 63 was 111.4%.

Next, when the phosphor of the example 63 was irradiated with themonochromatic light in the wavelength range from 250 nm to 550 nm, andthe excitation dependency of the emission intensity having thewavelength of 555.6 nm emitted from this phosphor was measured, it wasfound that, in the same way as the example 61, the excitation spectrumof this phosphor showed a green color emission with high intensity bythe excitation light in a broad wavelength range from about 300 nm to500 nm.

Next, the temperature characteristics of the emission intensity of thephosphor obtained by the example 63 were measured in the same way as theexample 61. This measurement result is shown in table 10, and further isshown in the same way as the example 61 by using a thick two dot chainline in FIGS. 14A and 14B.

From the result of FIG. 14A, when the phosphor of the example 63 wasirradiated with the monochromatic light having the wavelength of 460 nmas the excitation light, it was found that the emission intensity showed93.7% at the measurement temperature of 100° C., 84.1% at 200° C., and69.6% at 300° C., when the value of the emission intensity at the roomtemperature (25° C.) before increasing the measurement temperature wasset at 100%. After increasing the temperature, the phosphor was cooled,and the measurement at 25° C. again showed 97.1%, and almost no decreaseof emission intensity was observed, and even if it was observed, it waswithin a measurement error.

From the result of FIG. 14B, when the phosphor of the example 63 wasirradiated with the monochromatic light having the wavelength of 405 nmas the excitation light, the emission intensity showed 91.0% at themeasurement temperature of 100° C., 77.9% at 200° C., and 62.3% at 300°C., when the value of the emission intensity at the room temperature(25° C.) before increasing the measurement temperature was set at 100%.After increasing the temperature, the phosphor was cooled, and themeasurement at 25° C. again showed 97.5%, and almost no decrease ofemission intensity was observed, and even if it was observed, it waswithin a measurement error.

In the phosphor of the example 63, the molar ratio of Al, Si, N, and Owas slightly different from that of the phosphor of the examples 61 and62. However, the phosphor of the example 63 showed the excellentemission characteristics in the same way as the phosphor of the example61.

Example 64

In an example 64, the phosphor with a target composition after firinghaving the composition formula ofSrAl_(1.13)Si_(4.32)O_(0.64)N_(7.13):Ce (wherein Ce/(Sr+Ce)=0.030) wasmanufactured.

The phosphor of the example 64 having the composition formula expressedby SrAl_(1.13)Si_(4.32)O_(0.64)N_(7.13):Ce (wherein Ce/(Sr+Ce)=0.030)was manufactured in the same way as the example 61, other than each rawmaterial, SrCO₃ of 0.970 mol, Al₂O₃ of (1.06−0.976)/3 mol, AlN of1.00−((1.06−0.976)/3)×2 mol, Si₃N₄ of 4.5/3 mol, and CeO₂ of 0.030 mol,were weighed so that the molar ratio of each element wasSr:Al:Si:O:Ce=0.970:1.0:4.5:1.06:0.030. The analysis result, the averageparticle size (D50) and the specific surface area (BET) of themanufactured phosphor are shown in table 9. The specific surface area ofthe phosphor of the example 64 thus obtained was 0.254 m²/g. The averageparticle size (D50) was 24.08 μm. Note that although the example 64 hadthe same composition as that of the example 1, the example 64 has amixing composition in which an oxygen amount is increased by 0.06 mol ascompared to a mixing amount of the raw materials of the example 1.

Next, in the same way as the example 61, the emission spectrum of thephosphor of the example 64 was measured. This measurement result isshown in table 10. As shown in the table 10, when the phosphor wasirradiated with the monochromatic light having the wavelength of 460 nmas the excitation light, the emission spectrum of this phosphor had abroad peak in a broad wavelength range from 470 nm to 750 nm in the sameway as the phosphor of the example 61, and the peak wavelength was 559.2nm. The half value width was 118.8 nm, and the chromaticity (x, y) ofthis emission spectrum was x=0.4125 and y=0.5431. Note that thisphosphor powder had yellow fluorescent color and the green emissioncolor could be visually confirmed. When the relative intensity of theemission intensity in the phosphor of the example 61 was set at 100%,the relative intensity of the phosphor of the example 64 was 94.6%.

Next, as shown in the table 10, when the phosphor was irradiated withthe monochromatic light having the wavelength of 405 nm as theexcitation light, this phosphor had a broad peak in a broad wavelengthrange from 470 nmm to 750 nm in the same way as the phosphor of theexample 61, and the peak wavelength was 551.0 nm. The half value widthwas 121.5 nm, and the chromaticity (x, y) of this emission spectrum wasx=0.3699 and y=0.5343. Note that this phosphor powder had yellowfluorescent color, and the green emission color could be visuallyconfirmed. When the relative intensity of the emission intensity in thephosphor of the example 61 was set at 100%, the relative intensity ofthe phosphor of the example 64 was 105.3%.

Next, the phosphor of the example 64 was irradiated with themonochromatic light in the wavelength range from 250 nm to 550 nm, andthe excitation dependency of the emission intensity of the light havingthe wavelength of 559.2 nm emitted from this phosphor was measured.Then, it was found that in the same way as the phosphor of the example61, the excitation spectrum of this phosphor also showed the green coloremission with high intensity by the excitation light in a broadwavelength range form about 300 nm to 500 nm.

Next, in the same way as the example 61, the temperature characteristicsof the emission intensity of the phosphor thus obtained in the example64 were measured. These measurement results are shown in the table 10,and further shown in FIGS. 14A and 14B by using broken lines in the sameway as the example 1.

From the result of FIG. 14A, when the phosphor of the example 64 wasirradiated with the monochromatic light having the wavelength of 460 nmas the excitation light, the emission intensity showed 90.5% at themeasurement temperature of 100° C., 75.0% at 200° C., and 54.3% at 300°C., when the value of the emission intensity at the room temperature(25° C.) before increasing the measurement temperature was set at 100%.After increasing the temperature, the phosphor was cooled, and themeasurement at 25° C. again showed 81.8%, and the emission intensity wasdeteriorated by about 20%, as compared to an initial emission intensity.

From the result of FIG. 14B, when the phosphor of the example 64 wasirradiated with the monochromatic light having the wavelength of 405 nmas the excitation light, the emission intensity showed 89.3% at themeasurement temperature of 100° C., 72.3% at 200° C., and 51.9% at 300°C., when the value of the emission intensity at the room temperature(25° C.) before increasing the measurement temperature was set at 100%.After increasing the temperature, the phosphor was cooled, and themeasurement at 25° C. again showed 84.6%, and the emission intensity wasdeteriorated by about 20%, as compared to the initial emissionintensity.

Example 65

In an example 65, the phosphor having a target composition after firingexpressed by SrAl_(1.07)Si_(4.46)O_(0.70)N_(7.22):Ce (whereinCe/(Sr+Ce)=0.030) was manufactured. The phosphor of the example 65expressed by the composition formulaSrAl_(1.07)Si_(4.46)O_(0.70)N_(7.22):Ce (wherein Ce/(Sr+Ce)=0.030) wasobtained in the same way as the example 61, other than that duringmixing the raw materials, each raw material, SrCO₃ of 0.970 mol, Al₂O₃of (1.06−0.976)/3 mol, AlN of 1.00−((1.06−0.976)/3)×2 mol, Si₃N₄ of4.75/3 mol, and CeO₂ of 0.030 mol, were weighed so that the molar ratioof each element is Sr:Al:Si:O:Ce=0.970:1.0:4.75:1.06:0.030. An analysisresult, the average particle size (D50) and the specific surface area(BET) of the obtained phosphor powder are shown in table 9. The specificsurface area of the obtained phosphor was 0.212 m²/g. The averageparticle size (D50) was 25.44 μm.

Next, in the same way as the example 61, the emission spectrum of thephosphor of the example 65 was measured. This measurement result isshown in the table 10. As shown in the table 10, when the phosphor wasirradiated with the monochromatic light having the wavelength of 460 nmas the excitation light, the emission spectrum had a broad peak in abroad wavelength range from 470 nm to 750 nm in the same way as theexample 61, and the peak wavelength was 558.1 nm. Also, the half valuewidth was 117.2 nm, and the chromaticity (x, y) of the emission spectrumwas x=0.4114 and y=0.5445. Note that this phosphor powder had yellowfluorescent color and the green emission color could be visuallyconfirmed. When the relative intensity of the phosphor of the example 61was set at 100%, the relative intensity of the emission intensity of thephosphor of the example 65 was 93.4%.

Next, as shown in the table 10, when the phosphor was irradiated withthe monochromatic light having the wavelength of 405 nm as theexcitation light, the emission spectrum had a broad peak in a broadwavelength range from 470 nm to 750 nm in the same way as the example61, and the peak wavelength was 551.0 nm. Also, the half value width was119.4 nm, and the chromaticity (x, y) of the emission spectrum wasx=0.3728, and y=0.5384. Note that this phosphor powder had yellowfluorescent color and the green emission color could be visuallyconfirmed. When the relative intensity of the phosphor of the example 61was set at 100%, the relative intensity of the emission intensity of thephosphor of the example 65 was 104.6%.

Next, when the phosphor of the example 65 was irradiated with themonochromatic light in the wavelength range from 250 nm to 550 nm andthe excitation dependency of the emission intensity of the light havingthe wavelength of 558.1 nm emitted from this phosphor was measured, itwas found that in the same way as the example 61, the excitationspectrum of this phosphor also showed the green color emission with highintensity by the excitation light in a broad wavelength range from about300 nm to 500 nm.

Next, the temperature characteristics of the emission intensity of thephosphor of the example 65 were measured in the same way as the example61. This measurement result is shown in the table 10, and is furthershown in FIGS. 14A and 14B by using a thin one dot chain line in thesame way as the example 1.

From the result of FIG. 14A, when the phosphor of the example 65 wasirradiated with the monochromatic light having the wavelength of 460 nmas the excitation light, the emission intensity showed 90.4% at themeasurement temperature of 100° C., 73.4% at 200° C., and 51.7% at 300°C., when the value of the emission intensity at the room temperature(25° C.) before increasing the measurement temperature was set at 100%.After increasing the temperature, the phosphor was cooled, and themeasurement at 25° C. again showed 81.9%, and the emission intensity wasdeteriorated by about 15%, as compared to the initial emissionintensity.

From the result of FIG. 14B, when the phosphor of the example 65 wasirradiated with the monochromatic light having the wavelength of 405 nmas the excitation light, the emission intensity showed 88.7% at themeasurement temperature of 100° C., 70.4% at 200° C., and 48.9% at 300°C., when the value of the emission intensity at the room temperature(25° C.) before increasing the measurement temperature was set at 100%.After increasing the temperature, the phosphor was cooled, and themeasurement at 25° C. again showed 85.4%, and the emission intensity wasdeteriorated by about 15%, as compared to the initial emissionintensity.

Example 66

In an example 66, the phosphor having a target composition after firingexpressed by SrAl_(1.01)Si_(4.70)O_(0.65)N_(7.52):Ce(whereinCe/(Sr+Ce)=0.030) was manufactured. The phosphor of the example 66expressed by the composition formulaSrAl_(1.01)Si_(4.70)O_(0.65)N_(7.52):Ce(wherein Ce/(Sr+Ce)=0.030) wasobtained in the same way as the example 61, other than that duringmixing the raw materials, each raw material, SrCO₃ of 0.970 mol, Al₂O₃of (1.06-0.976)/3 mol, AlN of 1.00−((1.06−0.976)/3)×2 mol, Si₃N₄ of5.00/3 mol, and CeO₂ of 0.030 mol, were weighed so that the molar ratioof each element is Sr:Al:Si:O:Ce=0.970:1.0:5.00:1.06:0.030. A analysisresult, the average particle size (D50) and the specific surface area(BET) of the obtained phosphor powder are shown in the table 9. Thespecific surface area of the obtained phosphor was 0.256 m²/g. Theaverage particle size (D50) was 27.14 μm. Note that the example 66 showsthe mixing composition in which an amount of oxygen is increased by 0.06mol than the mixing amount of the raw materials of the example 2previously shown.

Next, in the same way as the example 61, the emission spectrum of thephosphor of the example 66 was measured. This measurement result isshown in the table 10. As shown in the table 10, when the phosphor wasirradiated with the monochromatic light having the wavelength of 460 nmas the excitation light, the emission spectrum of this phosphor had abroad peak in a broad wavelength range from 470 nm to 750 nm in the sameway as the phosphor of the example 61, and the peak wavelength was 559.2nm. Also, the half value width was 116.6 nm and the chromaticity (x, y)of the emission spectrum was x=0.4141, y=0.5444. Note that the powdershowed the fluorescent color of yellow, and the green emission colorcould be visually confirmed. When the relative intensity of the phosphorof the example 61 was set at 100%, the relative intensity of theemission intensity of the phosphor of the example 66 was 95.0%.

Next, as shown in the table 10, when the phosphor was irradiated withthe monochromatic light having the wavelength of 405 nm as theexcitation light, the emission spectrum had a broad peak in a broadwavelength range from 470 nm to 750 nm in the same way as the example61, and the peak wavelength was 550.9 nm. Also, the half value width was118.5 nm, and the chromaticity (x, y) of the emission spectrum wasx=0.3753, and y=0.5396. Note that this phosphor powder had yellowfluorescent color and the green emission color could be visuallyconfirmed. When the relative intensity of the phosphor of the example 61was set at 100%, the relative intensity of the emission intensity of thephosphor of the example 66 was 105.3%.

Next, when the phosphor of the example 66 was irradiated with themonochromatic light in the wavelength range from 250 nm to 550 nm andthe excitation dependency of the emission intensity of the light havingthe wavelength of 559.2 nm emitted from this phosphor was measured, itwas found that, in the same way as the phosphor of the example 61, theexcitation spectrum of this phosphor also showed green color emissionwith high intensity by the excitation light in a broad wavelength rangefrom about 300 nm to 500 nm.

Next, the temperature characteristics of the emission intensity of thephosphor thus obtained in the example 66 was measured in the same way asthe example 61. This measurement result is shown in the table 10, and isfurther shown in FIGS. 14A and 14B by using thin two dot chain lines inthe same way as the example 61.

From the result of FIG. 14A, when the phosphor of the example 66 wasirradiated with the monochromatic light having the wavelength of 460 nmas the excitation light, the emission intensity showed the values of90.4% at the measurement temperature of 100° C., 76.9% at 200° C., and60.1% at 300° C., when the value of the emission intensity at the roomtemperature (25° C.) before increasing the measurement temperature wasset at 100%. After increasing the temperature, the phosphor was cooled,and the measurement at 25° C. again showed 98.2%, and almost no decreaseof emission intensity was observed, and even if it was observed, it waswithin a measurement error.

From the result of FIG. 14B, when the phosphor of the example 66 wasirradiated with the monochromatic light having the wavelength of 405 nmas the excitation light, the emission intensity showed 89.0% at themeasurement temperature of 100° C., 73.2% at 200° C., and 55.5% at 300°C., when the value of the emission intensity at the room temperature(25° C.) before increasing the measurement temperature was set at 100%.After increasing the temperature, the phosphor was cooled, and themeasurement at 25° C. again showed 98.6%, and almost no decrease ofemission intensity was observed, and even if it was observed, it waswithin a measurement error.

Study on the Examples 61 to 66

As is obvious from the result of the table 10 and FIGS. 14A and 14B,samples of the examples 61 to 63 with Al/Sr being in a range of1.1<Al/Sr≦2.0 have excellent emission characteristics compared to thesamples of the examples 64 to 66 with Al/Sr being 1.0. The example 61had an excellent initial emission intensity by about 5.0% as compared tothe samples of the examples 64 to 66, and particularly the temperaturecharacteristics were significantly improved and the deterioration of theemission intensity could be more suppressed by about 4.0% at themeasurement temperature of 100° C. and 10.0% or more at 300° C. than thesamples of the examples 64 to 66, under the excitation wavelength of 460nm. Further, when these phosphors were cooled after increasing thetemperature and the emission intensity was measured again at 25° C., theemission intensity of the samples of the examples 64 to 65 with Al/Srbeing 1.0 were deteriorated by about 20% as compared to the emissionintensity before increasing the temperature. Meanwhile, thedeterioration of emission intensities of the phosphors of the examples61 to 63 were about 3.0%, and it was found that almost no deteriorationwas observed and the phosphor was excellent against heat. In the sameway as the phosphor of the examples 61 to 63, the emission intensity ofthe phosphor of the example 66 after being cooled is hardlydeteriorated. Meanwhile, the emission intensity during adding heat issignificantly deteriorated, and in the same way as the phosphor of theexample 64 and the example 65, the phosphor is deteriorated as comparedto the samples of the examples 61 to 63, and the same thing can be saidunder the excitation wavelength of 405 nm. In the phosphors of theexamples 61 to 63, optimization of Al concentration is performed overoxygen/nitrogen concentration of a production phase and thereforereduction of impurity phase is advanced and the emission characteristicsand the temperature characteristics are improved, as compared to thephosphors of the examples 64 to 66.

TABLE 9 AVERAGE SPECIFIC PARTICLE SURFACE Sr Al Si O N Ce OTHERS SIZEAREA (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) D50(μm) (m²/g)EXAMPLE 61 23.6 10.8 29.9 2.63 27.8 1.36 3.91 24.40 0.225 EXAMPLE 6222.8 9.66 30.9 2.79 29.8 1.21 2.84 24.21 0.264 EXAMPLE 63 24.6 10.1 27.83.36 28.6 1.50 4.07 25.77 0.231 EXAMPLE 64 22.6 8.06 32.2 2.72 28.8 1.044.58 24.08 0.254 EXAMPLE 65 22.4 7.58 33.0 2.93 28.8 1.06 4.23 25.440.212 EXAMPLE 66 21.7 6.98 33.8 2.64 29.8 1.14 3.94 27.14 0.256

TABLE 10 CHANGE RATE OF EMISSION INTENSITY RELATIVE AT EACH MEASUREMENTTEMPERATURE EXCITATION PEAK EMISSION (AFTER WAVE- WAVE- CHROMA-INTENSITY (TEMPERATURE INCREASING PROCESS) COOLING) LENGTH LENGTH TICITY(25° C.) 25° 50° 100° 150° 200° 250° 300° 25° (nm) (nm) x y (%) C. C. C.C. C. C. C. C. EXAMPLE 61 460 556.0 0.404 0.548 100.0 100.0 96.8 94.491.0 85.8 80.1 73.4 98.8 EXAMPLE 62 460 555.6 0.404 0.548 94.0 100.096.3 93.0 89.0 83.8 77.7 70.8 98.4 EXAMPLE 63 460 555.6 0.400 0.550 93.5100.0 96.5 93.7 89.5 84.1 77.4 69.6 97.1 EXAMPLE 64 460 559.2 0.4120.543 94.6 100.0 95.8 90.5 83.5 75.0 65.0 54.3 81.0 EXAMPLE 65 460 558.10.411 0.545 93.4 100.0 95.9 90.4 82.9 73.4 62.9 51.7 81.9 EXAMPLE 66 460559.2 0.414 0.544 95.0 100.0 95.6 90.4 84.0 76.9 68.4 60.1 98.2 EXAMPLE61 405 531.5 0.348 0.530 119.9 100.0 96.0 92.0 87.0 80.9 74.0 66.5 98.9EXAMPLE 62 405 533.5 0.351 0.534 110.9 100.0 95.7 90.9 85.4 78.8 72.064.6 98.6 EXAMPLE 63 405 530.4 0.343 0.530 111.4 100.0 95.9 91.0 84.877.9 70.2 62.3 97.5 EXAMPLE 64 405 551.0 0.370 0.534 105.3 100.0 95.589.3 81.5 72.3 62.4 51.9 84.6 EXAMPLE 65 405 551.0 0.373 0.538 104.6100.0 95.6 88.7 80.3 70.4 59.8 48.9 85.4 EXAMPLE 66 405 550.9 0.3750.540 105.3 100.0 95.5 89.0 81.4 73.2 64.3 55.5 98.6

(Powder X-Ray Diffraction Pattern)

In the examples 61 to 66, diffraction patterns obtained by a powderX-ray method are shown in FIG. 15.

From the results shown in FIG. 15, a product phase contained in thephosphor of the present invention has characteristic peaks in a Braggangle (28) ranges of 12.5 to 13.5°, 17.0 to 18.0°, 21.0 to 22.0°, 22.5to 23.5°, 26.5 to 27.5°, 28.5 to 29.5°, 34.0 to 35.0°, 35.5 to 36.5°,36.5 to 37.5°, 41.0 to 42.0°, 42.0 to 43.0°, 56.5 to 57.5°, 66.0 to67.0°. From this diffraction pattern, a crystal system of a main productphase of this phosphor is considered to be an orthorhombic system or amonoclinic system.

In a case of a/m≦1.1 (examples 64 to 66), the intensity of a strongestdiffraction peak observed in Bragg angle (2θ) range of 35.5° to 36.5° isdeteriorated as compared to a case of 1.1<a/m≦2.0 (examples 61 to 63).Meanwhile, in a case of 1.1<a/m≦2.0, the intensities of the diffractionpeaks observed in Bragg angle (2θ) ranges of 36.5° to 37.5°, 41.0° to42.0°, and 42.0° to 43.0° are enhanced as compared to a case of a/m≦1.1.This reveals that by increasing an amount of substitution of Al of theSi site, orientation properties of a crystal are changed, and byreducing the impurity phase not contributing to light emission, anexcellent emission efficiency can be exhibited even under a hightemperature environment. Thus, the phosphor having the excellentemission efficiency and showing the excellent emission efficiency evenunder the high temperature environment can be obtained.

Here, the measurement method of the X-ray diffraction pattern by thispowder method will be explained.

The phosphor to be measured was pulverized after firing up to aprescribed (preferably 1.0 μm to 50.0 μm) average particle size by usingpulverizing means such as a mortar and a ball mill, and a holder oftitanium was filled with the phosphor thus pulverized so that itssurface becomes flat, and the X-ray diffraction pattern of the phosphorwas measured by using an XRD device by RIGAKU DENKI INC., “RINT 2000”.

Measurement conditions are as follows.

Measuring instrument: “RINT 2000” by RIGAKU DENKI INC.

X-ray tube: CoKα

Tube voltage: 40 kV

Tube current: 30 mA

Scan method: 2θ/θ

Scan speed: 0.3°/min

Sampling interval: 0.01°

Start angle (2θ): 10°

Stop angle (2θ): 90°

The deviation of the Bragg angle (2θ) is possibly caused by an unevensample surface to be irradiated with X-ray, measurement conditions ofX-ray, and particularly the difference in scan speed. Therefore, aslight deviation would be allowable in the range where a characteristicdiffraction peak is observed. In order to suppress the deviation as muchas possible, Si is mixed in the phosphor sample, with the scan speed setat 0.3°/min, and the deviation of Si peak is corrected after X-raymeasurement, to thereby obtain the Bragg angle (2θ).

(Measurement of True Density)

Further, a true density measurement was performed for the samples of theexamples 61 to 63, and it was found that all of the samples show thevalues in the vicinity of 3.45 g/cc such as 3.43 g/cc, 3.45 g/cc, and3.46 g/cc. Note that an Ultrapycnometer 1000 by QUANTACHROME Inc., wasused for measuring the true density. When the impurity phase in theproduct phase is increased, the true density is increased or decreasedthan the aforementioned values, and therefore the true density of thephosphor of the present invention may be in a range of 3.45 g/cc±3% toobtain excellent emission characteristics and temperaturecharacteristics.

Examples 67 to 72

In the examples 67 to 72, the samples (examples 67 to 72), with a/mratio (here, a/m and Al/Sr have the same meaning) changed, weremanufactured, in the phosphor having composition formula of a targetcomposition after firing expressed bySrAl_(a)Si_(3.81)O_(0.59)N_(n):Ce(Ce/(Sr+Ce)=0.030, n=2/3m+a+4/3b−2/3o,m=1.0, b=3.81, o=0.59), and the peak wavelength, the chromaticity (x,y), the relative emission intensity at 25° C., and the temperaturecharacteristics were measured, as the emission characteristics in eachsample.

Here, in the manufacture of the phosphors of the examples 67 to 72, eachsample was manufactured in the same way as the example 61, other thanthat the mixing ratio of only AlN(3N) of each raw material of SrCO₃(3N), Al₂O₃(3N), AlN(3N), Si₃N₄(3N), CeO₂(3N) was adapted, and theemission intensity and the temperature characteristics of each samplethus manufactured were measured. The blending ratio of Al and Sradjusted was set at Al/Sr=1.10 (example 67), Al/Sr=1.21 (example 68),Al/Sr=1.38 (example 69), Al/Sr=1.43 (example 70), Al/Sr=1.66 (example71), Al/Sr=2.21 (example 72).

The results of the emission characteristics and the temperaturecharacteristics of each sample manufactured in the examples 67 to 72 areshown in table 11 and FIG. 16.

In the measurement of the emission intensity shown in the table 11, thevalues of the emission intensity of the samples (25° C.) of the examples67 to 72 were shown by the relative emission intensity, when the valueof the emission intensity at the time of irradiating the phosphor of theexample 70 with the monochromatic light having the wavelength of 460 nmas the excitation light was set at 100%. Next, the value of the emissionintensity at the room temperature (25° C.) before increasing themeasurement temperature was standardized as 100% for each sample, andthe measurement results of the change of the emission intensity at thetime of increasing the measurement temperature from 25° C. to 300° C.are shown. In addition, the table 11 shows the values of the emissionintensities when the samples are cooled again to 25° C. after increasingthe temperature of the samples up to 300° C. Note that the light havingthe wavelength of 460 nm was used as the excitation light.

FIG. 16 shows the measurement results of the temperaturecharacteristics, wherein the value of the relative emission intensity istaken on the ordinate axis, and the value of the measurementtemperature, at which the measurement of the emission intensity isperformed, is taken on the abscissa axis, and the example 67 is shown bya solid line, the example 68 is shown by a thick one dot chain line, theexample 69 is shown by a thick two dot chain line, the example 70 isshown by a thin one dot chain line, the example 71 is shown by a shortbroken line, and the example 72 is shown by a long broken line.

As is obvious from the results of the table 11 and FIG. 16, thephosphor, with Al/Sr being 1.43, shows most excellent emissioncharacteristics. Incidentally, the emission intensity was excellent byabout 8.0% at 25° C. before increasing the temperature as compared tothe case that Al/Sr was 1.10, and the deterioration of the emissionintensity was small in all temperature regions even when the temperaturewas increased, and the excellent temperature characteristics were shown.At the measurement temperature of 100° C., the deterioration of theemission intensity could be suppressed by about 4.5% as compared to thecase that Al/Sr was 1.10, and at the measurement temperature of 300° C.,the deterioration of the emission intensity could be suppressed by about20.0% as compared to the case that Al/Sr is 1.10.

In a region in which the value of Al/Sr is smaller than 1.43, thedeterioration of the emission intensity during increasing thetemperature can be suppressed with increase of this value. However, whenthe value of Al/Sr is made further larger, with a peak in the vicinityof Al/Sr=1.43 (example 70), the deterioration of the emission intensitybecomes large again, such as (P₂₅−P₁₀₀)/P₂₅×100>10.0 at the measurementtemperature of 100° C., when the value of Al/Sr is Al/Sr=2.21 (example72). In addition, in a region in which the value of Al/Sr is small, theemission intensity at 25° C. after increasing the temperature andcooling is significantly deteriorated after cooling as compared tobefore increasing the temperature. Meanwhile, in a region in which thevalue of Al/Sr is large, there is a problem that the initial emissionintensity is low even before increasing the temperature. Accordingly, inorder to obtain a sufficiently practical phosphor, the value of theAl/Sr is preferably in a range of 1.1<a/m≦2.0.

This is because the phosphor of the present invention is a nitride,oxynitride phosphor having a structure Sr with large ionic radius entersin a gap of an assembled network, being a structure in which a part ofSi of a tetrahedron structure of (SiN₄) is substituted with Al, and apart of N thereof is substituted with 0, which is different structurefrom conventional nitride and oxynitride phosphors. Namely, the reasonis that by having the network structure of (SiN₄) different from a caseof allowing Ca to enter, because Sr of the phosphor of the presentinvention has a larger ionic radius than Ca of Ca_(x) (Al,Si)₁₂(O,N)₁₆:Eu (wherein 0<x≦1.5), having the same tetrahedron structureof (SiN₄) as that of the phosphor of the present invention, and byhaving different Al substitution amount of Si and O substitution amountof N, the optimization is performed into a structure of the phosphorhaving the excellent emission characteristics. Then, it can beconsidered that by the optimization of the crystal structure, theactivator can be regularly present in this phosphor, and transfer ofexcitation energy used for light emission is efficiently performed, andtherefore the emission efficiency is improved. Further, this crystalstructure is nitride or oxynitride having high temperature resistance,generated by reaction of AlN and Si₃N₄. Therefore, it can be consideredthat almost no structure change occurs even when the temperature isincreased, and the deterioration of the emission intensity caused by theincrease of the temperature of the phosphor itself is suppressed.

TABLE 11 RELATIVE CHANGE RATE OF EMISSION INTENSITY PEAK EMISSION ATEACH MEASUREMENT TEMPERATURE WAVE- INTENSITY (AFTER LENGTH CHROMATICITY(25° C.) (TEMPERATURE INCREASING PROCESS) COOLING) Al/Sr (nm) x y (%)25□ 50□ 100□ 150□ 200□ 250□ 300□ 25□ EXAMPLE 67 1.10 559.7 0.413 0.54291.3 100.0 95.7 90.0 82.6 74.1 64.6 53.3 81.3 EXAMPLE 68 1.21 558.20.410 0.545 94.3 100.0 96.2 91.5 85.8 79.0 71.2 62.6 92.7 EXAMPLE 691.38 558.1 0.405 0.548 98.6 100.0 96.7 93.9 90.1 85.4 79.4 72.2 98.5EXAMPLE 70 1.43 556.0 0.404 0.548 100.0 100.0 96.8 94.4 91.0 85.8 80.173.4 98.8 EXAMPLE 71 1.66 556.2 0.400 0.546 72.4 100.0 95.6 92.0 87.482.1 75.9 69.3 97.6 EXAMPLE 72 2.21 558.1 0.405 0.543 64.9 100.0 93.987.9 81.2 74.6 67.5 60.6 96.8

Examples 73 to 75

In examples 73 to 75, samples of the example 73 to the example 75 weremanufactured, with a/m ratio (here, a/m and Al/Sr have the same meaning)changed in the phosphor with the composition formula of a targetcomposition after firing expressed bySrA_(a)Si_(4.09)O_(0.65)N_(n):Ce(Ce/(Sr+Ce)=0.030, n=2/3m+a+4/3b−2/3o,m=1.0, b=4.09, o=0.65), and the peak wavelength, the relative emissionintensity at 25° C., the temperature characteristics and thechromaticity (x, y) were measured as the emission characteristics ineach sample.

Here, in the manufacture of the phosphors of the examples 73 to 75, thephosphor samples were manufactured in the same way as the example 62,other than adapting, as was explained in the example 62, the mixingratio of only AlN (3N) out of each raw material of SrCO₃ (3N), Al₂O₃(3N), AlN (3N), Si₃N₄ (3N), and CeO₂(3N), and the emission intensity andthe temperature characteristics of each sample thus manufactured weremeasured. The mixing ratio of the adjusted Al and Sr was set atAl/Sr=1.07 (example 73), Al/Sr=1.33 (example 74), and Al/Sr=1.60(example 75).

The emission characteristics and the temperature characteristics of eachsample manufactured in the examples 73 to 75 are shown in table 12 andFIG. 17.

As shown in the table 12, the values of the emission intensities of theexamples 73 to 75(25° C.) are shown by the relative emission intensity,when the value of the emission intensity at the time of irradiating thephosphor of the example 75 with the monochromatic light having thewavelength of 460 nm as the excitation light (25° C.). Next, the valuesof the emission intensities at the room temperature (25° C.) beforeincreasing the measurement temperature are standardized as 100% for eachsample, and the measurement results of the change of emissionintensities at the time of increasing the measurement temperature from25° C. to 300° C. are shown. In addition, the table 12 also shows thevalues of the emission intensities when the temperature of the samplesare increased up to 300° C. and thereafter the samples are cooled againto 25° C. Note that the light having the wavelength of 460 nm was usedas the excitation light.

FIG. 17 shows the measurement result of the temperature characteristics,wherein the value of the relative emission intensity is taken on theordinate axis and the emission intensity is taken on the abscissa axis,and the example 73 is shown by solid line, the example 74 is shown byone dot chain line, and the example 75 is shown by two dot chain line.

As is obvious from the result of the table 12 and FIG. 17, the phosphorexhibited most excellent emission characteristics, with Al/Sr being inthe vicinity of 1.33 to 1.60. Incidentally, Al/Sr is more excellent thana case of 1.07 by about 9.0% at 25° C. before increasing thetemperature, and even when the temperature is increased, thedeterioration of the emission intensity is small in all of thetemperature range at the time of increasing the temperature, therebyexhibiting the excellent temperature characteristics. At the measurementtemperature of 100° C., the deterioration of the emission intensitycould be suppressed by about 4.0%, compared to the case that Al/Sr is1.07, and at the measurement temperature of 300° C., the deteriorationof the emission intensity could be suppressed by about 20% compared tothe case that Al/Sr is 1.07. Moreover, when Al/Sr is 1.07, the emissionintensity at 25° C. after increasing/decreasing the temperature is moredeteriorated by about 17% than a case before increasing the temperature.Meanwhile, almost no deterioration of the emission intensity occurs whenAl/Sr is 1.33 and 1.60, and even if it occurs, it is within a level ofmeasurement error.

As described above, in the same way as the examples 67 to 72, it wasfound that a sufficiently practicable phosphor could also be obtained inthe examples 73 to 75, provided that Al/Sr was within a range of1.1<a/m≦2.0. In the examples 73 to 75, since the molar ratios of Si arelarger than those of the examples 67 to 72, optimal range of Al/Sr isslightly different.

TABLE 12 CHANGE RATE OF EMISSION INTENSITY RELATIVE AT EACH MEASUREMENTTEMPERATURE PEAK EMISSION (AFTER WAVE- INTENSITY (TEMPERATURE INCREASINGPROCESS) COOLING) LENGTH CHROMATICITY (25° C.) 25° 50° 100° 150° 200°250° 300° 25° (nm) x y (%) C. C. C. C. C. C. C. C. EXAMPLE 73 558.20.412 0.544 91.0 100.0 95.3 89.3 81.7 72.0 61.5 50.7 82.6 EXAMPLE 74555.6 0.404 0.548 100.0 100.0 96.3 93.0 89.0 83.8 77.7 70.8 98.4 EXAMPLE75 555.8 0.398 0.549 97.2 100.0 96.0 93.2 89.9 85.5 79.9 73.2 96.5

Examples 76 to 79

In examples 76 to 79, samples of the example 76 to the example 79 weremanufactured, with o/m ratio (here, o/m and Al/Sr have the same meaning)changed in the phosphor with the composition formula of a targetcomposition after firing expressed by SrAl_(1.43)Si_(3.81)O_(o)N_(n):Ce(Ce/(Sr+Ce)=0.030, n=2/3m+a+4/3b−2/3o, m=1.0, a=1.43, b=3.81), and thepeak wavelength, the relative emission intensity at 25° C., thetemperature characteristics and the chromaticity (x, y) were measured asthe emission characteristics in each sample.

Here, in the manufacture of the phosphors of the examples 76 to 79, thephosphor sample was manufactured in the same way as the example 61,other than adapting, as was explained in the example 61, the mixingratios of Al₂O₃(3N) and AlN(3N) out of each raw materials of SrCO₃(3N),Al₂O₃(3N), AlN(3N), Si₃N₄(3N), and CeO₂(3N) were adjusted and theemission intensity and the temperature characteristics of each samplethus manufactured were measured. The mixing ratio of the adjusted O andSr was set at O/Sr=0.48 (example 76), O/Sr=0.59 (example 77), O/Sr=0.70(example 78), and O/Sr=0.81 (example 79).

The results of the emission characteristics and the temperaturecharacteristics of each sample manufactured in the examples 76 to 79 areshown in table 13 and FIG. 18A.

In the measurement of the emission intensity shown in the table 13, thevalue of the emission intensity (25° C.) of the examples 76 to 79 wasshown by the relative emission intensity, when the value of the emissionintensity at 25° C. when the phosphor of the example 77 was irradiatedwith the monochromatic light having the wavelength of 460 nm. Next, thevalue of the emission intensity at the room temperature of 25° C. beforeincreasing the measurement temperature was standardized as 100% for eachsample, and the measurement result of the change of the emissionintensity at the time of increasing the measurement temperature from 25°C. to 300° C. is shown. In addition, the table 13 also shows the valueof the emission intensity when the temperature of the sample isincreased up to 300° C. and is cooled again down to 25° C. Note that thelight having the wavelength of 460 nm was used as the excitation light.

FIG. 18A shows the measurement result of the temperaturecharacteristics, wherein the value of the relative emission intensity istaken on the ordinate axis, and the value of the measurementtemperature, at which the measurement of the emission intensity isperformed, is taken on the abscissa axis, and the example 76 is shown bya solid line, the example 77 is shown by one dot chain line, the example78 is shown by two dot chain line, and the example 79 is shown by abroken line.

FIG. 18B is a graph showing a relation between oxygen content and therelative emission intensity in each sample, wherein the relativeemission intensity is taken on the ordinate axis and the oxygen contentin each sample is taken on the abscissa axis.

As is obvious from the results of the table 13, FIG. 18A, and FIG. 18B,the phosphor, with O/Sr being 0.59, shows most excellent emissioncharacteristics. Incidentally, the emission intensity was excellent byabout 17.0% at 25° C. before increasing the temperature as compared tothe case that O/Sr is 0.48, and the deterioration of the emissionintensity was small in all temperature regions even when the temperaturewas increased, and the excellent temperature characteristics were shown.At the measurement temperature of 100° C., the deterioration of theemission intensity could be suppressed by about 3.0% as compared to thecase that 0/Sr was 0.48, and at the measurement temperature of 300° C.,the deterioration of the emission intensity could be suppressed by about6.0% as compared to the case that O/Sr is 0.48.

Although in this example, the value of Al/Sr is set at 1.43 (best valuein the examples 67 to 72), the temperature characteristics of theexample 76 is slightly deteriorated compared to other samples. However,in a range of this example, an excellent result regarding thetemperature characteristics of each sample is obtained, irrespective ofthe value of 0/Sr. Meanwhile, the initial emission intensity issignificantly affected by the value of O/Sr, and it was found that theinitial emission intensity was improved by 10%, as compared to a case ofother values, when the value of 0/Sr is in the vicinity of O/Sr=0.59,being an optimal value. Then, when the value of O/Sr is within a rangeof 0.0<o/m≦1.5, more preferably within a range of 0.0<o/m≦1.0, asufficiently practicable phosphor can be obtained.

In the present invention, the reason seems to be as follows. Although apart of Si of a tetrahedron structure of (SiN4) is substituted with Al,when only the Al substitution amount is changed, the crystal structureis deviated from the structure suitable for light emission because Alhas a larger ionic radius than that of Si, and further the valency of anentire body of a matrix structure is unstable because Si has the valencyof IV while Al has the valency of III. However, when apart of site N issubstituted with 0 having smaller ionic radius than N, the crystalstructure suitable for light emission can be taken, and further theexcellent emission characteristics can be exhibited because the valencyof the entire body of the matrix structure becomes stable zero.

TABLE 13 CHANGE RATE OF EMISSION INTENSITY RELATIVE AT EACH MEASUREMENTTEMPERATURE PEAK EMISSION (AFTER WAVE- INTENSITY (TEMPERATURE INCREASINGPROCESS) COOLING) LENGTH CHROMATICITY (25° C.) 25° 50° 100° 150° 200°250° 300° 25° O N (nm) x y (%) C. C. C. C. C. C. C. C. (wt %) (wt %)EXAMPLE 76 558.2 0.408 0.545 82.8 100.0 95.5 91.4 86.2 80.4 74.2 67.498.3 2.46 29.0 EXAMPLE 77 556.0 0.404 0.548 100.0 100.0 96.8 94.4 91.085.8 80.1 73.4 98.8 2.63 27.8 EXAMPLE 78 555.6 0.399 0.549 87.8 100.096.7 94.0 90.2 85.3 79.4 72.6 97.6 3.61 26.8 EXAMPLE 79 554.7 0.3950.549 79.4 100.0 97.1 93.9 90.0 85.4 79.0 71.9 96.1 4.39 27.9

Examples 80 to 82

In the examples 80 to 82, the samples of examples 80 to 82, with o/mratio (here, o/m and O/Sr have the same meaning) changed, weremanufactured, in the phosphor having composition formula of a targetcomposition after firing expressed bySrAl_(1.33)Si_(4.09)O_(o)N_(n):Ce(Ce/(Sr+Ce)=0.030, n=2/3m+a+4/3b−2/3o,m=1.0, a=1.33, b=4.09), and the peak wavelength, the chromaticity (x,y), the relative emission intensity at 25° C., and the temperaturecharacteristics were measured, as the emission characteristics in eachsample.

Here, in the manufacture of the phosphors of the examples 80 to 82, eachphosphor sample was manufactured in the same way as the example 62,other than adapting the mixing ratio of Al₂O₃(3N) and AlN(3N) of eachraw material of SrCO₃(3N), Al₂O₃(3N), AlN(3N), Si₃N₄(3N), CeO₂(3N), andthe emission intensity and the temperature characteristics of eachsample thus manufactured were measured. The blending ratio of O and Sradjusted was set at O/Sr=0.52 (example 80), O/Sr=0.65 (example 81), andO/Sr=0.77 (example 82).

The result of the emission characteristics and the temperaturecharacteristics of each sample manufactured in the examples 80 to 82 isshown in table 14 and FIG. 19A.

In the measurement of the emission intensity shown in the table 14, thevalues of the emission intensity of the samples (25° C.) of the examples80 to 82 were shown by the relative emission intensity, when the valueof the emission intensity at the time of irradiating the phosphor of theexample 81 with the monochromatic light having the wavelength of 460 nmas the excitation light (25° C.) was set at 100%. Next, the value of theemission intensity at the room temperature (25° C.) before increasingthe measurement temperature was standardized as 100% for each sample,and the measurement result of the change of the emission intensity atthe time of increasing the measurement temperature from 25° C. to 300°C. was shown. In addition, the table 14 shows the value of the emissionintensity when the sample is cooled again to 25° C. after increasing thetemperature of the sample up to 300° C. Note that the light having thewavelength of 460 nm was used as the excitation light.

FIG. 19A shows the measurement result of the temperaturecharacteristics, wherein the value of the relative emission intensity istaken on the ordinate axis, and the value of the measurementtemperature, at which the measurement of the emission intensity isperformed, is taken on the abscissa axis, and the example 80 is shown bya solid line, the example 81 is shown by one dot chain line, and theexample 82 is shown by two dot chain line.

Also FIG. 19B is a graph showing a relation between oxygen content andthe relative emission intensity in each sample, wherein the relativeemission intensity is taken on the ordinate axis and the oxygen contentin each sample is taken on the abscissa axis.

As is obvious from the result of the table 14, FIG. 19A, and FIG. 19B,the phosphor of this example shows most excellent emissioncharacteristics, when the value of O/Sr is 0.65. For example, the valueof 0/Sr is more excellent by about 5.0% than a case of 0.52 beforeincreasing the temperature (25° C.), and even when the temperature isincreased, the deterioration of the emission intensity is slightlysmaller in an entire temperature region, thus exhibiting the excellenttemperature characteristics. At the measurement temperature of 100° C.,the deterioration of the emission intensity can be suppressed in a rangeof (P₂₅−P₁₀₀)/P₂₅×100≦10.0, and at the measurement temperature of 300°C., the deterioration of the emission intensity can be suppressed byabout 3.4% as compared to a case that the value of O/Sr is 0.52.

Regarding the temperature characteristics of the phosphor of thisexample, since the value of Al/Sr is set at 1.33 (best value in theexamples 73 to 75), an excellent result is obtained in a range of thisexample, irrespective of the value of O/Sr. However, the initialemission intensity is significantly affected by the value of O/Sr, andit was found that the initial emission intensity was largest at the caseof O/Sr=0.65, being the optimum value, and for example, was larger byabout 25.0% as compared to a case of O/Sr=0.77. Then, in the examples 80to 82 also, in the same way as the case of the examples 76 to 79, whenthe value of O/Sr is within a range of 0.0<o/m≦1.5, more preferablywithin a range of 0.0<o/m≦1.0, a sufficiently practicable phosphor canbe obtained.

Here, Al molar ratio and Si molar ratio are different between theexamples 80 to 82 and the examples 76 to 79. Therefore, a tendency ofthe optimal value of o/m in the examples 80 to 82 is slightly differentfrom the examples 76 to 79. Particularly, difference is observed in theinitial emission intensity in the vicinity of O/Sr=0.50, and in theexamples 76 to 79, the initial emission intensity is deteriorated byabout 17.0% as compared to the initial emission intensity under theoptimal value of O/Sr=0.59. However, in the examples 80 to 82, theinitial emission intensity is deteriorated only by about 5.0% ascompared to the optimal value of O/Sr=0.65. Accordingly, it is foundthat the optimal value of O/Sr is not determined independently, but ischanged according to the Al substitution amount of the site Si.

TABLE 14 CHANGE RATE OF EMISSION INTENSITY RELATIVE AT EACH MEASUREMENTTEMPERATURE PEAK EMISSION (AFTER WAVE- INTENSITY (TEMPERATURE INCREASINGPROCESS) COOLING) LENGTH CHROMATICITY (25° C.) 25° 50° 100° 150° 200°250° 300° 25° O N (nm) x y (%) C. C. C. C. C. C. C. C. (wt %) (wt %)EXAMPLE 80 557.3 0.407 0.546 94.5 100.0 96.3 92.7 87.7 81.7 74.6 67.499.0 2.50 28.6 EXAMPLE 81 555.6 0.404 0.548 100.0 100.0 96.3 93.0 89.083.8 77.7 70.8 98.4 2.79 29.8 EXAMPLE 82 557.2 0.401 0.547 76.0 100.097.0 93.1 88.6 82.7 75.9 68.3 97.8 3.69 29.6

Hereunder, in the examples 83 to 92, evaluation was made for thephosphor mixture and the light emission device using the phosphors ofthe aforementioned examples 1 and example 61. In comparative examples 4to 8, the evaluation was made for the phosphor mixture and the lightemission device using a conventional green phosphor.

Example 83

In an example 83, the emission characteristics and the color renderingproperties were evaluated when the phosphor sample SrAlSi_(4.5)ON₇:Ce(wherein Ce/(Sr+Ce)=0.030) of the example 1 of the present invention wasexcited by using the light emitting element (LED) emitting the lighthaving the wavelength of 460 nm. However, the emission wavelength of thelight emitting element may be in an excitation band range from 300 nm to500 nm where efficiency of this phosphor is excellent, and is notlimited to the wavelength of 460 nm.

First, the LED element (emission wavelength of 467 nm) of blue lightusing a nitride semiconductor was prepared as a light emission part.Further, the phosphor prepared by the example 1, epoxy resin, and adispersant were mixed to obtain a mixture. Note that regarding theresin, it is preferable to set the transmittance and the refractiveindex to be higher, and not only epoxy-based resin but alsosilicone-based resin may be satisfactory provided that theaforementioned condition is satisfied. Fine particles such as SiO₂ maybe slightly mixed in the dispersant. Then, by sufficiently stirring thismixture, which was then applied on the LED light element by aconventional process, a white LED illumination (light emission device)was manufactured. Since the emission color and the emission efficiencyare changed by the ratio of the phosphor and the resin in theaforementioned mixture and the thickness of coating, the condition maybe adjusted in accordance with a target color temperature.

FIG. 20 shows the emission spectrum when power of 20 mA is applied tothe manufactured white LED illumination. FIG. 20 is a graph showing therelative emission intensity taken on the ordinate axis and the emissionwavelength (nm) taken on the abscissa axis. Then, the emission spectrumof the white LED illumination of the example 83 is shown by a solidline.

This phosphor emitted light under excitation of blue light emitted bythe light emission part, and emitted light of white light having theemission spectrum with a broad peak continuously in the wavelength rangefrom 400 nm to 750 nm, and the white LED illumination was therebyobtained. When the color temperature, chromaticity, and color renderingproperties of this light emission were measured, it was found that thecolor temperature was 6078K, x=0.317, and y=0.374. Moreover, an generalcolor rendering index (Ra) of this white LED lamp was 73. Further, bysuitably changing the blending amount of the phosphor and the resin, theemission color with different color temperature could be obtained.

Example 84

In the example 84, in the same way as the example 83, the emissioncharacteristics and the color rendering properties of this phosphor wereevaluated when the phosphor of SrAl_(1.43)Si_(3.81)O_(0.59)N_(6.79):Ceof the example 61 of the present invention was excited by using thelight emitting element (LED) emitting light having the wavelength of 460nm.

FIG. 21 shows the emission spectrum when the power of 20m A is appliedto the white LED illumination manufactured by the same manufacturingmethod as that of the example 83. FIG. 21 is a graph showing therelative emission intensity taken on the ordinate axis, and the emissionwavelength (nm) taken on the abscissa axis. Then, the emission spectrumof the white LED illumination of the example 84 is shown by a solidline.

This phosphor was excited to emit light by the blue light emitted by thelight emission part, and emitted white light having the emissionspectrum with a broad peak continuously in the wavelength range from 400nm to 750 nm, and the white LED illumination was thereby obtained. Whenthe color temperature, chromaticity, and the color rendering propertiesof this light emission were measured, it was found that the colortemperature was 6344K, the chromaticity was x=0.3115, y=0.3649, and thegeneral color rendering index Ra was 72.

Examples 85 and 86

In an example 85 or an example 86, the phosphor mixture wasmanufactured, which emits light of correlated color temperature of 5000K(example 85) or 3000K (example 86), when the red phosphor was furtheradded to the phosphor of the example 61 and the phosphor mixture wasthen excited by the light emitting element (LED) emitting light havingthe wavelength of 460 nm. Then, the emission characteristics and thecolor rendering properties of this phosphor mixture were evaluated. Notethat in this example, CaSiAlN₃:Eu was used as the red phosphor, howeverthe red phosphor having nitrogen such as Sr₄AlSi₁₁O₂N₁₇:Eu, (Ca,Sr)₂Si₅N₈:Eu or a sulfide-based red phosphor such as SrS:Eu, CaS:Eu canalso be used.

1) Preparation of the Phosphor Sample

The green phosphor SrAl_(1.43)Si_(3.81)O_(0.59)N_(6.79):Ce (phosphor ofthe example 61) was manufactured by the method explained in the example61. Meanwhile, the red phosphor CaSiAlN₃:Eu was manufactured by a methoddescribed hereunder.

Commercially available Ca3N2 (2N), AlN (3N), Si3N4 (3N), and Eu2O3 (3N)were prepared, and each raw material was weighed so that the molar ratioof each element was Ca:Al:Si:Ce=0.970:1.00:1.00:0.030, and was mixed byusing a mortar in a nitrogen atmosphere. The temperature of mixed rawmaterials was increased at a temperature-rising rate of 15° C./min up to1500° C. in a powder state under a nitrogen atmosphere. Then, the rawmaterials were retained/fired for 12 hours at 1500° C., and thereafterwere cooled for 1 hour from 1500° C. down to 200° C., to thereby obtainthe phosphor having the composition formula expressed by CaSiAlN₃:Eu.The sample thus obtained was pulverized, classified, and a red phosphorsample was prepared.

2) Manufacture of the Phosphor Mixture

The emission spectrum for two kinds of phosphor samples such asSrAl_(1.43)Si_(3.81)O_(0.59)N_(6.79):Ce and CaSiAlN₃:Eu under excitationby excitation light having the wavelength of 460 nm were respectivelymeasured, and from the emission spectra, relative mixing ratios toachieve 5000K (example 85) or 3000K (example 86) of the correlated colortemperature of both phosphor mixtures were obtained by simulation.According to the results of this simulation, when the correlated colortemperature was 5000K (example 85), the molar ratio wasSrAl_(1.43)Si_(3.81)O_(0.59)N_(6.79):Ce:CaAlSiN₃:Eu=98.0:2.0 (molarratio), and when the correlated color temperature was 3000K (example86), the molar ratio wasSrAl_(1.43)Si_(3.81)O_(0.59)N_(6.79):Ce:CaAlSiN₃:Eu=95.0:5.0 (molarratio). Based on these results, each phosphor was weighed and thephosphor mixtures were obtained.

However, by the emission wavelength of the light emission part(excitation wavelength of the phosphor mixture) and the emissionefficiency of the phosphor to the excitation light, a preferable mixingratio is sometimes deviated from this simulation result. In this case,the blending ratio of the phosphors is suitably adjusted, and an actualemission spectrum shape is arranged.

3) Evaluation by the Light Emitting Element

In the same way as the examples 83 and 84, the LED (having the emissionwavelength of 460 nm) of blue light having the nitride semiconductor wasprepared as the light emission part, and on this LED, the mixture of theaforementioned phosphor mixture and resin was set. Regarding the mixingratio of the phosphor mixture and the resin, a suitable blending ratioof the phosphors were adjusted so as to obtain a daylight white colorcorresponding to the color temperature of 5000K and a warm colorcorresponding to 3000K, based on the simulation result, which was thencombined with the light emission part of the LED, and the white colorLED illumination (light emission device) were thereby manufactured, by aconventional process.

The aforementioned both phosphor mixtures were excited/emitted light bythe blue light emitted by the light emission part, and the white LEDilluminations emitting white light having the emission spectra with abroad peak in the wavelength range from 420 nm to 750 nm could beobtained. Here, the emission spectra when the power of 20 mA was fed tothe light emitting element of the manufactured white LED illuminationare shown in FIG. 21. In FIG. 21, the emission spectrum of daylightwhite color of the white LED illumination set to have the colortemperature of 5000K is shown by one dot chain line, and the emissionspectrum of warm color of the white LED illumination set to have thecolor temperature of 3000K is shown by two dot chain line.

Here, list of measurement data such as luminance, chromaticity, colorrendering index, and color temperature of the white LED illumination ofthe example 85 or the example 86 is shown in table 15.

When the color temperature, chromaticity, or color rendering propertiesof the light emission were measured, the white LED illumination of theexample 85 set to have the color temperature of 5000K showed the colortemperature of 4987K, x=0.3454, y=0.3512, the general color renderingindex Ra of 90, and a special color rendering index R9 of 84, R13 of 91,and R15 of 91. The white color LED illumination of the example 86 set tohave the color temperature of 3000K showed the color temperature of2999K, x=0.4362, y=0.4024, the general color rendering index Ra of 95,and the special color rendering index R9 of 89, R13 of 99, and R15 of97. Further, in these white LED illuminations, by suitably changing theblending amount of the phosphors to be mixed and the blending amount ofresin, the emission color of different color temperature could also beobtained.

TABLE 15 GENERAL COLOR COLOR RENDERING TEMPERATURE CHROMATICITY INDEXSPECIAL COLOR RENDERING INDEX Tcp(K) x y Ra R9 R10 R11 R12 R13 R14 R15EXAMPLE 85 4987 0.3454 0.3512 90 84 77 81 48 91 93 91 EXAMPLE 86 29990.4362 0.4024 95 89 87 95 69 99 92 97

Next, examples 87 to 89 will be explained.

In the examples 87 to 89, the phosphor mixture emitting light of thecorrelated color temperature of 6500K when excited by the light emittingelement (LED) emitting light having the wavelength of 405 nm, wasmanufactured and the emission characteristics and the color renderingproperties of this phosphor mixture were evaluated. Further, in theexample 89, two kinds of red phosphors were added, and excellent colorrendering properties were obtained and the luminance was improved. Here,BAM:Eu(BaMgAl₁₀O₁₇:Eu) and (Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu were used as bluephosphors. However, the phosphors are not limited thereto, and thephosphors expressed by Sr₅(PO₄)₃Cl:Eu,SrAl_(x)Si_(6−X)O_(1+X)N_(8−x):Eu(0≦x≦2), (Ba,Sr,Ca,Mg)₂SiO₄:Eu,(Ba,Sr,Ca)Si₂O₂N₂:Eu may be combined.

Example 87 1) Preparation of Phosphor

The green phosphor Sr₂Al₂Si₁₀ON₁₆:Ce was manufactured and prepared by amethod as described hereunder.

Commercially available SrCO₃(2N), AlN(3N), Si₃N₄(3N), CeO₂(3N) wereprepared. These raw materials were weighed and mixed to obtain themixing ratio of the respective raw materials in SrCO₃ of 0.970 mol, AlNof 1.0 mol, Si₃N₄ of 5/3 mol, and CeO₂ of 0.030 mol, so that the molarratio of each element becomes Sr:Al:Si:Ce=0.970:1:5:0.030. The rawmaterials thus mixed were set in a nitrogen atmosphere (flow state, 20.0L/min) in a powder state, and the temperature was increased up to 1800°C. at a rate of 15° C./min, with an in-furnace pressure set at 0.05 MPa,which were then retained/fired at 1800° C. for 3 hours, and thereafterthe temperature was decreased from 1800° C. down to 50° C. to cool theraw materials for one hour and half. Thereafter, fired samples werepulverized in an atmospheric air by using the mortar until the sampleshave a proper particle size, and the phosphor having a mixed compositionformula expressed by Sr₂Al₂Si₁₀₀N₁₆:Ce was prepared.

The red phosphor CaAlSiN₃:Eu was manufactured by the method explained inthe example 85.

A commercially available blue phosphor BAM:Eu(BaMgAl₁₀O₁₇:Eu) wasprepared.

2) Manufacture of Phosphor Mixture

The emission spectra for three kinds of phosphor samples such asSr₂Al₂Si₁₀ON₁₆:Ce, CaAlSiN₃:Eu, and BAM:Eu under excitation byexcitation light having the wavelength of 405 nm were respectivelymeasured, and from these emission spectra, the relative mixing ratio toachieve 6500K of the correlated color temperature of the phosphormixtures was obtained by simulation. According to the result of thissimulation, the molar ratio wasBAM:Eu:Sr₂Al₂Si₁₀ON₁₆:Ce:CaAlSiN₃:Eu=47.6:49.5:2.9, and therefore basedon this result, each phosphor was weighed and the phosphor mixture wasobtained.

Here, under the excitation by the excitation light having the wavelengthof 405 nm, the half value width of the emission spectrum of BAM:Eu was53.5 nm, the half value width of the emission spectrum ofSr₂Al₂Si₁₀ON₁₆:Ce was 118.0 nm, and the half value width of the emissionspectrum of CaAlSiN₃:Eu was 86.7 nm, all of which were 50 nm or more.

However, a preferable mixing ratio is sometimes deviated from the resultof the simulation, depending on the emission wavelength of the lightemission part (excitation wavelength of the phosphor mixture) and theemission efficiency of the phosphor with this emission wavelength. Inthis case, by suitably adjusting the blending ratio of the phosphors, anactual shape of the emission spectrum may be arranged.

3) Evaluation of the Emission Characteristics

The phosphor mixture thus obtained was irradiated with the light havingthe wavelength of 405 nm as the excitation light, and the correlatedcolor temperature of the light emission of this phosphor mixture wasmeasured. Then, it was found that the correlated color temperature was6512K and this phosphor mixture had a target color temperature. Further,when the chromaticity of this light emission was measured, x=0.312 andy=0.331 was obtained. A value of the luminance (Y) was obtained based ona calculation method in the XYZ color system defined by JISZ8701, andthe luminance was set at 100.

It was found that the luminance of the phosphor mixture of the example87 was increased by about 18%, as compared to the luminance of thephosphor mixture of the comparative example 4 as will be describedlater.

The emission spectrum is shown by a thick solid line in FIG. 22. FIG. 22is a graph showing the relative emission intensity taken on the ordinateaxis and the emission wavelength (nm) on the abscissa axis. The emissionspectrum has three emission peaks in the wavelength range from 420 nm to680 nm and had a continuous spectrum without being interrupted in thewavelength range from 420 nm to 750 nm.

4) Evaluation of the Color Rendering Property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was performed based on the JISZ8726. Then, it wasfound that the general color rendering index Ra was 97 and the specialcolor rendering index R9 was 93 and R15 was 95, and an extremelyexcellent color rendering property was exhibited.

A list of the measurement data of the luminance, chromaticity, colorrendering index, and color temperature, etc, obtained from the example87 and examples 88, 89, and comparative examples 4 to 6 as will bedescribed later is shown in a table 16.

Example 88 1) Preparation of the Phosphor

Sr₂Al₂Si₁₀ON₁₆:Ce was prepared by the method explained in the example87, as the green phosphor.

CaAlSiN₃:Eu was prepared by the method explained in the example 85, asthe red phosphor.

Commercially available (Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu was prepared as theblue phosphor.

2) Manufacture of the Phosphor Mixture

Under the same simulation as the example 87, (Sr, Ca, Ba,Mg)₁₀(PO₄)₆Cl₂:Eu:Sr₂Al₂Si₁₀ON₁₆:Ce:CaAlSiN₃:Eu=64.5:33.1:2.4 wasobtained, and based on this result, each phosphor was weighed and mixedto obtain the phosphor mixture.

Here, the half value width of the emission spectrum of(Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu was 51.1 nm, when the phosphor was excitedby the excitation light having the wavelength of 405 nm.

3) Evaluation of the Emission Characteristics

In the same way as the example 87, when the correlated color temperatureof the light emission of this phosphor mixture was measured, it was6502K, thus exhibiting a target color temperature. Further, when thechromaticity of this light emission was measured, x=0.313 and y=0.327was obtained. When the luminance was obtained from the obtained emissionspectrum, it was found that the luminance of the phosphor mixture ofthis example was 101, when the luminance of the example 87 was set at100.

The luminance of the phosphor mixture of the example 88 was increased byabout 16%, as compared to the luminance of the phosphor mixture of thecomparative example 5 as will be described later.

The obtained emission spectrum is shown by a thick one dot chain line inFIG. 22.

In the same way as the example 87, this emission spectrum had threeemission peaks in the wavelength range from 420 nm to 680 nm and acontinuous spectrum without being interrupted in the wavelength rangefrom 420 nm to 750 nm.

4) Evaluation of the Color Rendering Property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was performed based on the JISZ8726. Then, it wasfound that the general color rendering index Ra was 94, the specialcolor rendering index R9 was 60, R15 was 89, and an extremely excellentcolor rendering property was exhibited.

Example 89

In an example 89, the phosphor mixture emitting light having thecorrelated color temperature of 6500K when excited by the light emittingelement (LED) emitting the light having the wavelength of 405 nm wasmanufactured by a method of using two kinds of red phosphors havingfurther improved luminance and color rendering properties, and theemission characteristics and color rendering properties of this phosphormixture was evaluated.

1) Preparation of the Phosphor

Sr₂Al₂Si₁₀₀N₁₆:Ce was prepared by the method explained in the example87, as the green phosphor.

CaAlSiN₃:Eu was prepared by the method explained in the example 85, asthe red phosphor.

Commercially available BAM:Eu was prepared as the blue phosphor.

In addition, a second red phosphor CaAl₂Si₄N₈:Eu was manufactured by thefollowing method.

Commercially available Ca₃N₂ (2N), AlN (3N), Si₃N₄ (3N), Eu₂O₃ (3N) wereprepared and each raw material was weighed, so that the molar ratio ofeach element was Ca:Al:Si:Eu=0.970:2:4:0.030, and mixed in the glove boxunder the nitrogen atmosphere by using the mortar. Then, the temperaturewas increased at a rate of 15° C./min up to 1700° C. in the nitrogenatmosphere, and the raw materials were retained and fired for 3 hours at1700° C., and the temperature was decreased from 1700° C. to 200° C. for1 hour, to obtain the phosphor having the composition formula expressedby CaAl₂Si₄N₈:Eu. Then, the phosphor was pulverized and classified.

2) Manufacture of the Phosphor Mixture

Under the same simulation as the example 87,BAM:Eu:Sr₂Al₂Si₁₀ON₁₆:Ce:CaAl₂Si₄N₈:Eu:CaAlSiN₃:Eu=48.7:48.1:1.0:2.2 wasobtained and based on this result, each phosphor was weighed and mixedto obtain the phosphor mixture.

3) Evaluation of the Emission Characteristics

In the same way as the example 87, when the correlated color temperatureof the light emission of this phosphor mixture was measured, it was6496K, thus exhibiting a target color temperature. Further, when thechromaticity of this light emission was measured, x=0.313, y=0.329 wasobtained. When the luminance was obtained from the obtained emissionspectrum, the luminance of the phosphor mixture of this example was 107,with the luminance of the example 87 set at 100.

The luminance of the phosphor mixture of the example 89 was increased byabout 2%, as compared to the luminance of the phosphor mixture of acomparative example 6 as will be described later.

The obtained emission spectrum is shown by a thick two dot chain line inFIG. 22.

In the same way as the example 87, this emission spectrum had threeemission peaks in the wavelength range from 420 nm to 680 nm and had acontinuous spectrum without being interrupted in the wavelength rangefrom 420 nm to 750 nm.

4) Evaluation of the Color Rendering Property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was performed based on the JISZ8726. The generalcolor rendering index Ra was 95, the special color rendering index R9was 92, R15 was 97, and it was found that an extremely excellent colorrendering property was exhibited.

Next, the phosphor mixture manufactured by using an already known greenphosphor is shown as a comparative example. In the comparative examples4 to 6, the phosphor mixtures emitting light having the correlated colortemperature of 6500K when excited by the light emitting element (LED)emitting the light having the wavelength of 405 nm were manufactured,and the emission characteristics and the color rendering properties ofthese phosphor mixture were evaluated. The comparative example 6 usedtwo kinds of red phosphors, and was compared to the example 89 havingthe improved color rendering property and the luminance.

Comparative Example 4 1) Preparation of the Phosphor

Commercially available ZnS:Cu,Al was prepared as the green phosphor.

CaAlSiN₃:Eu was prepared by the method explained in the example 85, asthe red phosphor.

Commercially available BAM:Eu was prepared as the blue phosphor.

2) Manufacture of the Phosphor Mixture

The simulation similar to that of the example 87 was performed, and arelative mixing ratio of BAM:Eu: ZnS:Cu,Al:CaAlSiN₃:Eu=61.1:27.4:11.5was obtained, so that the correlated color temperature of the emissionspectrum of the phosphor mixture under the excitation light having thewavelength of 405 nm was 6500K, and based on this result, each phosphorwas weighed and mixed to obtain the phosphor mixture.

3) Evaluation of the Emission Characteristics

In the same way as the example 87, when the correlated color temperatureof the light emission of this phosphor mixture was measured, it was6518K, thus exhibiting a target color temperature. Further, when thechromaticity of this light emission was measured, x=0.311, y=0.337 wasobtained. When the luminance was obtained from the obtained emissionspectrum, it was found that the luminance of the phosphor mixture ofthis example was 82, with the luminance of the example 87 set at 100.

The obtained emission spectrum is shown by a thin broken line in FIG.22.

This emission spectrum had three emission peaks in the wavelength rangefrom 420 nm to 680 nm and a continuous spectrum without beinginterrupted in the wavelength range from 420 nm to 750 nm.

4) Evaluation of the Color Rendering Property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was performed based on the JISZ8726. Then, it wasfound that the general color rendering index Ra was 87, and the specialcolor rendering index R9 was 6, R15 was 78.

Comparative Example 5 1) Preparation of the phosphor

Commercially available ZnS:Cu,Al was prepared as the green phosphor.

CaAlSiN₃:Eu was prepared by the method explained in the example 85, asthe red phosphor.

Commercially available (Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu was prepared as theblue phosphor.

2) Manufacture of the Phosphor Mixture

The simulation similar to that of the example 87 was performed, and arelative mixing ratio of (Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu:ZnS:Cu,AlCaAlSiN₃:Eu=74.3:19.3:6.4 was obtained, so that the correlated colortemperature of the emission spectrum of the phosphor mixture under theexcitation light having the wavelength of 405 nm was 6500K, and based onthis result, each phosphor was weighed and mixed to obtain the phosphormixture.

3) Evaluation of the Emission Characteristics

In the same way as the example 87, when the correlated color temperatureof the light emission of this phosphor mixture was measured, it was6481K, thus exhibiting a target color temperature. Further, when thechromaticity of this light emission was measured, x=0.313, y=0.329 wasobtained. When the luminance was obtained from the obtained emissionspectrum, the luminance of the phosphor mixture of this example was 85,with the luminance of the example 87 set at 100. The obtained emissionspectrum is shown by a thin one dot chain line in FIG. 22.

4) Evaluation of the Color Rendering Property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was performed based on the JIS8726. Then, it wasfound that the general color rendering index Ra was 75, the specialcolor rendering index R9 was −59, R15 was 57.

Comparative Example 6

In the comparative example 6, the phosphor mixture having furtherimproved luminance and color rendering properties emitting light havingthe correlated color temperature of 6500K when excited by the lightemitting element (LED) emitting light having the wavelength of 405 nm,was manufactured by using the already known green phosphor, two kinds ofred phosphors, and the already known blue phosphor, and the emissioncharacteristics and the color rendering properties of this phosphormixture were evaluated.

1) Preparation of the Phosphor

Commercially available ZnS:Cu,Al was prepared as the green phosphor.

CaAl₂Si₄N₈:Eu and CaAlSiN₃:Eu were prepared by the method explained inthe example 89, as the red phosphors.

Commercially available BAM:Eu was prepared as the blue phosphor.

2) Manufacture of the Phosphor Mixture

In the same way as the example 89, the relative mixing ratio ofBAM:Eu:ZnS:Cu,Al:CaAl₂Si₄N₈:Eu CaAlSiN₃:Eu=60.19:30.50:4.65:4.65 wasobtained, so that the correlated color temperature of the emissionspectrum of the phosphor mixture under the excitation light having thewavelength of 405 nm was 6500K, and based on this result, each phosphorwas weighed and mixed to obtain the phosphor mixture.

3) Evaluation of the Emission Characteristics

In the same way as the example 87, when the correlated color temperatureof the light emission of this phosphor mixture was measured, it was6568K, thus exhibiting a target color temperature. Further, when thechromaticity of this light emission was measured, x=0.314, y=0.322 wasobtained. When the luminance was obtained from the obtained emissionspectrum, the luminance of the phosphor mixture of this example was 105,with the luminance of the example 87 set at 100.

The obtained emission spectrum is shown by a thin two dot chain line inFIG. 22.

4) Evaluation of the color rendering property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was performed based on the JISZ8726. Then, thegeneral color rendering index Ra was 96, the special color renderingindex R9 was 84, R15 was 92.

TABLE 16 GENERAL COLOR COLOR RENDERING LUMINANCE TEMPERATURECHROMATICITY INDEX SPECIAL COLOR RENDERING INDEX (%) Tcp(K) x y Ra R9R10 R11 R12 R13 R14 R15 EXAMPLE 87 100 6512 0.312 0.331 97 93 97 97 8798 99 96 EXAMPLE 88 101 6502 0.313 0.327 94 60 92 91 93 93 98 89 EXAMPLE89 107 6496 0.314 0.322 95 92 95 94 86 98 98 97 COMPARATIVE 82 65180.311 0.337 87 6 97 87 87 90 92 78 EXAMPLE 4 COMPARATIVE 85 6481 0.3130.329 75 −59 82 67 93 77 90 57 EXAMPLE 5 COMPARATIVE 105 6568 0.3130.318 96 80 97 97 86 96 97 92 EXAMPLE 6

Next, in the examples 90 to 91, the phosphor mixtures emitting lighthaving the correlated color temperature of 4200K, when excited by thelight emitting element (LED) emitting the light having the wavelength of405 nm, were manufactured and the emission characteristics and the colorrendering properties of these phosphor mixtures were evaluated. In theexample 91, two kinds of red phosphors were used and the color renderingproperties and luminance were improved.

Example 90 1) Preparation of the Phosphor

In the same way as the example 87, Sr₂Al₂Si₁₀ON₁₆:Ce was prepared as thegreen phosphor, and CaAlSiN₃:Eu was prepared as the red phosphor, andBAM:Eu was prepared as the blue phosphor.

2) Manufacture of the Phosphor Mixture

In the same way as the example 87, the emission spectra when three kindsof phosphors such as BAM:Eu, Sr₂Al₂Si₁₀ON₁₆:Ce, and CaAlSiN₃:Eu wereexcited by the excitation light having the wavelength of 405 nm, weremeasured, and the relative mixing ratio to achieve the correlated colortemperature of 4200K of the phosphor mixture was obtained from theseemission spectra by simulation. A simulation result showed BAM:EuSr₂Al₂Si₁₀ON16:Ce:CaAlSiN₃:Eu=33.2:40.8:6.0, and therefore based on thisresult, each phosphor was weighed and mixed to obtain the phosphormixture.

3) Evaluation of the Emission Characteristics

In the same way as the example 87, the obtained phosphor mixture wasirradiated with the light having the wavelength of 405 nm, and when thecorrelated color temperature of the light emission of this phosphormixture was measured, it was 4205K, thus exhibiting a target colortemperature. Further, when the chromaticity of this light emission wasmeasured, x=0.373, y=0.376. The value of luminance (Y) is obtained basedon a calculation method in the XYZ color system defined by JISZ8701, andthe luminance was set at 100.

The luminance of the phosphor mixture of the example 90 was increased byabout 5%, as compared to the luminance of the phosphor mixture of acomparative example 7 as will be described later.

This emission spectrum had three emission peaks in the wavelength rangefrom 420 nm to 680 nm and had a continuous spectrum without beinginterrupted in the wavelength range from 420 nm to 750 nm.

The obtained emission spectrum is shown by a thick solid line in FIG.23.

Note that in the same way as FIG. 22, FIG. 23 is a graph showing therelative emission intensity taken on the ordinate axis, and the emissionwavelength (nm) taken on the abscissa axis.

4) Evaluation of the Color Rendering Property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was performed based on the JISZ8726. Then, it wasfound that the general color rendering index Ra was 95, the specialcolor rendering index R9 was 73, R15 was 92, and an extremely excellentcolor rendering property was exhibited.

The list of the measurement data of the luminance, chromaticity, colorrendering index, and color temperature, etc, of the example 90, and anexample 91 and comparative examples 7 and 8 as will be described later,are shown in table 17.

Example 91

In the example 91, the phosphor mixture emitting light having thecorrelated color temperature of 4200K when excited by the light emittingelement (LED) emitting light having the wavelength of 405 nm, wasmanufactured by using two kinds of red phosphors having further improvedluminance and color rendering properties, and the emissioncharacteristics and color rendering properties of this phosphor mixturewere evaluated.

1) Preparation of the phosphor

The green phosphor Sr₂Al₂Si₁₀ON₁₆:Ce was manufactured by the methodexplained in the example 87.

The red phosphor CaAlSiN₃:Eu was manufactured by the method explained inthe example 85. In addition, a second red phosphor CaAl₂Si₄N₈:Eu wasmanufactured by the method explained in the example 89.

Commercially available BAM:Eu was prepared as the blue phosphor.

2) Manufacture of the Phosphor Mixture

In the same way as the example 87,BAM:Eu:Sr₂Al₂Si₁₀ON₁₆:Ce:CaAl₂Si₄N₈:Eu:CaAlSiN₃:Eu=35.6:57.4:2.7:4.3were obtained by simulation, and based on this result, each phosphor wasweighed and mixed to obtain the phosphor mixture.

3) Evaluation of the Emission Characteristics

In the same way as the example 87, when the correlated color temperatureof the light emission of this phosphor mixture was measured, it was4189K, thus having a target color temperature. Further, when thechromaticity of this light emission was measured, x=0.373, y=0.372 wasobtained. When the luminance was obtained from the obtained emissionspectrum, the luminance of the phosphor mixture of this example was 107,with the luminance of the example 90 set at 100.

The luminance of the phosphor mixture of the example 91 was increased byabout 5%, as compared to the luminance of the phosphor mixture of acomparative example 8 as will be described later.

The obtained emission spectrum is shown by a thick one dot chain line inFIG. 23.

In the same way as the example 87, this emission spectrum had threeemission peaks in the wavelength range from 420 nm to 680 nm and had acontinuous spectrum without being interrupted in the wavelength rangefrom 420 nm to 750 nm.

4) Evaluation of the Color Rendering Property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was performed based on the JISZ8726. The generalcolor rendering index Ra was 95, the special color rendering index R9was 80, R15 was 94, and an extremely excellent color rendering propertywas exhibited.

Next, a phosphor mixture using an already known green phosphor is shownas a comparative example.

In the comparative examples 7 and 8, the phosphor mixtures emittinglight of the correlated color temperature of 4200K when excited by thelight emitting element (LED) emitting light having the wavelength of 405nm, were manufactured and the emission characteristics and colorrendering property of these phosphor mixtures were evaluated. Thecomparative example 8 shows a comparative example corresponding to theexample 91 wherein the color rendering property and the luminance wereimproved by adding two kinds of red phosphors.

Comparative Example 7

In the comparative example 7, the phosphor mixture emitting light havingthe correlated color temperature of 4200K was manufactured and theemission characteristics and color rendering properties of this phosphormixture were evaluated.

1) Preparation of the Phosphor

Commercially available ZnS:Cu,Al was prepared as the green phosphor.

CaAlSiN₃:Eu was prepared as the red phosphor.

Commercially available BAM:Eu was prepared as the blue phosphor.

2) Manufacture of the Phosphor Mixture

The relative mixing ratio of BAM:Eu:ZnS:Cu,Al:CaAlSiN₃:Eu=39.6:43.7:16.7 was obtained, so that thecorrelated color temperature of the emission spectrum of the phosphormixture under the excitation light having the wavelength of 405 nm was4200K, and based on this result, each phosphor was weighed and mixed toobtain the phosphor mixture.

3) Evaluation of the Emission Characteristics

In the same way as the example 87, when the correlated color temperatureof the light emission of this phosphor mixture was measured, it was4193K, thus having a target color temperature. Further, when thechromaticity of this light emission was measured, x=0.374, y=0.378 wasobtained. When the luminance was obtained from the obtained emissionspectrum, the luminance of the phosphor mixture of this comparativeexample was 95, with the luminance of the example 90 set at 100.

The obtained emission spectrum is shown by a thin broken line in FIG.23.

In the same way as in the example 87, this emission spectrum had threeemission peaks in the wavelength range from 420 nm to 680 nm and had acontinuous spectrum without being interrupted in the wavelength rangefrom 420 nm to 750 nm.

4) Evaluation of the Color Rendering Property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was evaluated based on the JISZ8726. Then, it wasfound that the general color rendering index Ra was 70, and the specialcolor rendering index R9 was −53, R15 was 54.

Comparative Example 8

In the comparative example 8, the phosphor mixture having further higherluminance and color rendering property emitting light having thecorrelated color temperature of 4200K when excited by the light emittingelement (LED) emitting light having the wavelength of 405 nm, wasmanufactured by using an already known green phosphor, two kinds of redphosphors and the blue phosphor, and the emission characteristics andcolor rendering properties of this phosphor mixture were evaluated, as acomparative example corresponding to the example 91.

1) Preparation of the phosphor

Commercially available ZnS:Cu,Al was prepared as the green phosphor.

The red phosphor CaAlSiN₃:Eu was manufactured by the method explained inthe example 85, as the red phosphor. In addition, the second redphosphor CaAl₂Si₄N₈:Eu was manufactured by the method explained in theexample 89.

Commercially available BAM:Eu was prepared as the blue phosphor.

2) Manufacture of the Phosphor Mixture

According to the simulation similar to that of the example 87, therelative mixing ratio of BAM:Eu:ZnS:Cu,Al:CaAl₂Si₄N₈:Eu:CaAlSiN₃:Eu=52.0:29.5:9.2:9.3 was obtained, sothat the correlated color temperature of the emission spectrum of thephosphor mixture under the excitation light having the wavelength of 405nm was 4200K, and based on this result, each phosphor was weighed andmixed to obtain the phosphor mixture.

3) Evaluation of the Emission Characteristics

In the same way as the example 87, when the correlated color temperatureof the light emission of this phosphor mixture was measured, it was4167K, thus having a target color temperature. Further, when thechromaticity of this light emission was measured, x=0.374, y=0.373 wasobtained. When the luminance was obtained from the obtained emissionspectrum, the luminance of the phosphor mixture of this comparativeexample was 102, with the luminance of the example 90 set at 100.

The obtained emission spectrum is shown by a thin two dot chain line inFIG. 23.

4) Evaluation of the Color Rendering Property

The evaluation of the color rendering property in the light emission ofthis phosphor mixture was performed based on the JISZ8726. The generalcolor rendering index Ra was 96, and the special color rendering indexR9 was 92, and R15 was 97.

TABLE 17 GENERAL COLOR COLOR RENDERING LUMINANCE TEMPERATURECHROMATICITY INDEX SPECIAL COLOR RENDERING INDEX (%) Tcp(K) x y Ra R9R10 R11 R12 R13 R14 R15 EXAMPLE 90 100 4205 0.373 0.376 95 73 96 96 8995 98 92 EXAMPLE 91 107 4189 0.373 0.372 95 80 96 93 85 97 100 94COMPARATIVE 95 4193 0.374 0.378 70 −53 81 61 91 73 87 54 EXAMPLE 7COMPARATIVE 102 4167 0.374 0.373 96 92 90 95 82 97 96 97 EXAMPLE 8

Example 92 Evaluation with Light Emitting Elements

The LED (having emission peak wavelength of 403.5 nm) of ultravioletlight having a nitride semiconductor was set as a light emission part,and a mixture of the phosphor sample obtained by the example 1 and resinwas set on the LED. The mixing ratio of this phosphor and the resin wasadjusted so as to obtain a daylight color corresponding to the colortemperature of 6500K based on the aforementioned result, and a white LEDwas manufactured by combining with the light emission part of this LEDby a publicly known method. As a result, FIG. 24 shows the emissionspectrum at the time of feeding power of 20 mA to the light emittingelement of the white LED thus obtained.

Note that in the same way as FIG. 22, FIG. 24 is a graph showing therelative emission intensity taken on the ordinate axis and the emissionwavelength (nm) taken on the abscissa axis.

This phosphor was excited to emit light by the ultraviolet light emittedby the light emission part, and the light was mixed with the blue coloremitted from the light emission part, thus making it possible to obtainthe white LED emitting white light. When the color temperature orchromaticity of this light emission was measured, the color temperaturewas 6469K, and x=0.312, y=0.331. Moreover, the general color renderingindex (Ra) of the white LED was 97, and the special color renderingindex R9 was 90, and R15 was 96. Further, by suitably changing theblending amount of the phosphor to be mixed and the blending amount ofthe resin, the emission color of different color temperature could alsobe obtained.

The list of the measurement data of the luminance, chromaticity, colorrendering index, and color temperature, etc, of the example 92 is shownin table 18.

TABLE 18 GENERAL COLOR COLOR RENDERING TEMPERATURE CHROMATICITY INDEXSPECIAL COLOR RENDERING INDEX Tcp(K) x y Ra R9 R10 R11 R12 R13 R14 R15EXAMPLE 92 6469 0.312 0.331 97 90 98 98 89 98 99 96

Example 93

In the example 93, the phosphor sheet was manufactured by dispersing thephosphor mixture manufactured in the example 84 into the resin, and thewhite LED was manufactured by combining this phosphor sheet and the LEDelement.

First, by using the silicone-based resin as the resin, being a medium,10 wt % of phosphor mixture of the example 84 was dispersed in theresin, and the phosphor sheet was manufactured. Next, as shown in thedesignation mark 1 of FIG. 26(C), the LED in which the phosphor sheetwas set on the LED element that emits light having the wavelength of 405nm was manufactured. Then, when this LED is allowed to emit light, thewhite light can be emitted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a SEM photograph of phosphor powders of an example 1.

FIG. 2 is a graph showing emission spectra when phosphors of examples 1to 3 and comparative examples 1 and 2 are irradiated with monochromaticlight having the wavelength of 460 nm.

FIG. 3 is a graph showing emission spectra when the phosphors of theexamples 1 to 3 and the comparative examples 1 and 2 are irradiated withthe monochromatic light having the wavelength of 405 nm.

FIG. 4 is a graph showing excitation spectra of the phosphors of theexamples 1 and 2.

FIG. 5 is a graph showing an excitation spectrum of the phosphor of theexample 3.

FIG. 6 is a graph showing a relation between a concentration of anactivator Z(Ce) and an emission intensity, in the phosphors of examples4 to 13.

FIG. 7 is a graph showing a relation between a concentration of anactivator Z(Eu) and an emission intensity, in the phosphors of examples14 to 23.

FIG. 8 is a graph showing a relation between Al/Sr ratio and an emissionintensity, in the phosphors of examples 24 to 32.

FIG. 9 is a graph showing a relation between Si/Sr ratio and an emissionintensity, in the phosphors of examples 33 to 42.

FIG. 10 is a graph showing a relation between Sr molar ratio and anemission intensity, in the phosphors of examples 43 to 50.

FIG. 11 is a graph showing a relation between oxygen content and anemission intensity, in the phosphors of examples 51 to 60.

FIG. 12 is an emission spectrum of the phosphor of the example 61.

FIG. 13 is an excitation spectrum of the phosphor of the example 61.

FIG. 14A is a graph showing measurement results of temperaturecharacteristics of the emission intensity, when the phosphors ofexamples 61 to 66 are excited by the light having the wavelength of 460nm.

FIG. 14B is a graph showing the measurement results of the temperaturecharacteristic of the emission intensity, when the phosphors of theexamples 61 to 66 are excited by the light having the wavelength of 405nm.

FIG. 15 shows X-ray diffraction patterns of the phosphors of theexamples 61 to 66.

FIG. 16 is a graph showing the measurement results of the temperaturecharacteristics of the emission intensity of the phosphors of examples67 to 72.

FIG. 17 is a graph showing the measurement results of the temperaturecharacteristics of the emission intensity of the phosphors of examples73 to 75.

FIG. 18A is a graph showing the measurement results of the temperaturecharacteristics of the emission intensity of the phosphors of examples76 to 79.

FIG. 18B is a graph showing a relation between the emission intensityand the oxygen content of the phosphors of the examples 76 to 79.

FIG. 19A is a graph showing the measurement results of the temperaturecharacteristics of the emission intensity of the phosphors of examples80 to 82.

FIG. 19B is a graph showing the relation between the emission intensityand the oxygen content of the phosphors of the examples 80 to 82.

FIG. 20 shows an emission spectrum of a white LED illumination of theexample 83.

FIG. 21 shows emission spectra of the white LED illuminations ofexamples 84 to 86.

FIG. 22 shows emission spectrum patterns when a correlated colortemperature is set at 6500K, in a phosphor mixtures of examples 87 to 89and comparative examples 4 to 6.

FIG. 23 is emission spectrum patterns when the correlated colortemperature is set at 4200K, in the phosphor mixtures of examples 90,91, and comparative examples 7 and 8.

FIG. 24 is a spectrum pattern of the light emitting element when thecorrelated color temperature is set at 6500K, in the phosphor mixture ofexample 92.

FIG. 25 is a graph showing an excitation spectrum of a conventionalyellow phosphor YAG:Ce.

FIG. 26A-C is a sectional view of a bullet type LED of an example.

FIG. 27A-E is a sectional view of a reflective type LED of an example.

DESCRIPTION OF SIGNS AND NUMERALS

-   -   1 Phosphor mixture    -   2 LED light emitting element    -   3 Lead frame    -   4 Resin    -   5 Cup-shaped container    -   8 Reflective surface    -   9 Transparent mold material

1. A phosphor of the composition formula MmAaBbOoNn:Z, wherein element Mis at least one element having bivalent valency selected from the groupconsisting of Mg, Ca, Sr, Ba, and Zn, element A is Al, element B is Si,O is oxygen, N is nitrogen, and element Z is Eu, Ce of a mixturethereof, satisfying 4.0<(a+b)/m<7.0, a/m≧0.5, b/a>2.5, n>o, n=2/3m+a+4/3b−2/3o, wherein when excited by light in a wavelength range from300 nm to 500 nm, the phosphor has an emission spectrum with a peakwavelength in a range from 500 nm to 650 nm.
 2. The phosphor accordingto claim 1, wherein when the composition formula is MmAaBbOoNn:Zz, thevalue of z/(m+z), which is a molar ratio of the element M to the elementZ, is 0.0001 or more and 0.5 or less.
 3. The phosphor according to claim1, containing Sr of 19.5 to 29.5 wt %, Al of 5.0 to 16.8 wt %, O of 0.5to 8.1 wt %, N of 22.6 to 32.0 wt %, and Ce of 0 to 3.5 wt %, whereinwhen the phosphor is irradiated with more than one kind of monochromaticlight or continuous light in the wavelength range from 350 nm to 500 nmas an excitation light, a peak wavelength in the emission spectrum is ina range from 500 to 600 nm, and x of chromaticity (x, y) of the emissionspectrum is in a range from 0.3000 to 0.4500, and y of the chromaticity(x, y) is in a range from 0.5000 to 0.6000.
 4. The phosphor according toclaim 1, containing Sr of 19.5 to 29.5 wt %, Al of 5.0 to 16.8 wt %, Oof 0.5 to 8.1 wt %, N of 22.6 to 32.0 wt %, and Eu of 0 to 3.5 wt %,wherein when the phosphor is irradiated with more than one kind ofmonochromatic light or continuous light in a wavelength range from 350nm to 500 nm as an excitation light, the peak wavelength of the emissionspectrum is in a range from 550 to 650 nm, and x of the chromaticity ofthe emission spectrum (x, y) is in a range from 0.4500 to 0.6000, and yof the chromaticity of the emission spectrum (x, y) is in a range from0.3500 to 0.5000.
 5. The phosphor according to claim 4, wherein when thephosphor is irradiated with the monochromatic light having thewavelength range from 350 nm to 500 nm as an excitation light, therelation of PH and PL satisfies (PH−PL)/PH×100 20, when a peak intensityof a maximum peak in a spectrum of light emission that occurs byabsorbing the excitation light that makes it highest is defined as PH,and the peak intensity of the maximum peak in the spectrum of lightemission that occurs by absorbing the excitation light that makes itsmallest is defined as PL.
 6. The phosphor according to claim 1, whereinwhen the value of relative intensity of the maximum peak in the emissionspectrum is defined as P25 when the phosphor is irradiated with aspecified monochromatic light in the wavelength range from 300 nm to 500nm at 25° C. as the excitation light, and the value of the relativeintensity of the maximum peak is defined as P200 when the phosphor isirradiated with the specified monochromatic light as the excitationlight at 200° C. the relation of P25 and P200 satisfies(P25−P200)/P25×100
 35. 7. The phosphor according to claim 1, containinga primary particle with particle size of 50 m or less and aggregates inwhich the primary particle agglutinates, wherein an average particlesize (D50) of the powdery phosphor containing the primary particle andthe aggregates is 1.0 μm or more and 50.0 μm or less.
 8. The phosphoraccording to claim 1, containing a primary particle with particle sizeof 20 m or less and aggregates in which the primary particleagglutinates, wherein an average particle size (D50) of the powderyphosphor containing the primary particle and the aggregates is 1.0 μm ormore and 20.0 μm or less.
 9. A phosphor mixture, comprising: thephosphor according to claim 1; more than one kind of blue phosphorshaving the emission spectrum with the maximum peak in the wavelengthrange from 420 nm to 500 nm, when excited by said excitation light inthe wavelength range from 300 nm to 500 nm; and/or more than one kind ofred phosphors having the emission spectrum with the maximum peak in thewavelength range from 590 nm to 680 nm, when excited by said excitationlight in the wavelength range from 300 nm to 500 nm.
 10. A phosphormixture, comprising: the phosphor according to claim 1; more than onekind of blue phosphors having the emission spectrum in the wavelengthrange from 420 nm to 500 nm, when excited by said excitation light inthe wavelength range from 300 nm to 420 nm; and more than one kind ofred phosphor having the emission spectrum with the maximum peak in thewavelength range from 590 nm to 680 nm, when excited by said excitationlight in the wavelength range from 300 nm to 420 nm.
 11. The phosphormixture according to claim 9, wherein when an emission intensity of eachphosphor constituting a mixture at a temperature of 25° C. when thisphosphor is excited by a prescribed excitation light in the wavelengthrange from 300 nm to 500 nm is defined as P25, and the emissionintensity at the temperature of 200° C. when this phosphor is irradiatedwith said prescribed excitation light is defined as P200, the relationof P25 and P200 is given satisfying (P25−P200)/P25×100
 30. 12. Thephosphor mixture according to claim 10, wherein when an emissionintensity of each phosphor constituting a mixture at a temperature of25° C. when this phosphor is excited by a prescribed excitation light inthe wavelength range from 300 nm to 500 nm is defined as P25, and theemission intensity at the temperature of 200° C. when this phosphor isirradiated with said prescribed excitation light is defined as P200, therelation of P25 and P200 is given satisfying (P25−P200)/P25×100
 30. 13.The phosphor mixture according to claim 9, wherein in the emissionspectrum under excitation of the excitation light in the wavelengthrange from 300 nm to 420 nm, a correlated color temperature is in arange from 7000K to 2500K, with three or more emission peaks in thewavelength range from 420 nm to 750 nm and with a continuous spectrumwithout being interrupted in the wavelength range from 420 nm to 750 nm.14. The phosphor mixture according to claim 9, wherein the phosphormixture is composed of a phosphor having an average particle size (D50)of 1 μm or more and 50 μm or less.
 15. A light emission device,comprising the phosphor according to claim 1 and a light emission partfor emitting light of a first wavelength, wherein the light of adifferent wavelength from the first wavelength is emitted from thephosphor, by using a part or an entire part of the light of the firstwavelength as an excitation light.
 16. The light emission device,comprising the phosphor mixture according to claim 9 and the lightemission part for emitting light of the first wavelength, wherein thelight of the different wavelength from the first wavelength is emittedfrom the phosphor, by using a part or an entire part of the light of thefirst wavelength as an excitation light.
 17. A light emission deviceaccording to claim 15, wherein the first wavelength is the wavelength of350 nm to 500 nm.
 18. The light emission device according to claim 15,wherein the correlated color temperature of the light emission device isin a range from 10000K to 2000K.
 19. The light emission device accordingto claim 15, wherein an average color rendering index Ra of the lightemission device is 80 or more.
 20. The light emission device accordingto claim 15, wherein the light emission part is a light emitting diode(LED).